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# Influence of surface texturing on the biocompatibility of breast implants

Charles Garabedian

► To cite this version:

Charles Garabedian. Influence of surface texturing on the biocompatibility of breast implants: upstream and clinical approaches. Engineering Sciences [physics]. Université Polytechnique Hauts-de-France, 2019. English. NNT: 2019UPHF0007. tel-03359321

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# Thèse de doctorat

## Pour obtenir le grade de Docteur de

## l'UNIVERSITÉ POLYTECHNIQUE HAUTS-DE-FRANCE

Discipline, spécialité selon la liste des spécialités pour lesquelles l'Ecole Doctorale est accréditée :
**MECANIQUE**

Présentée et soutenue par Charles, GARABEDIAN.

Le 25/10/2019, à Valenciennes

**Ecole doctorale :**

Sciences Pour l'Ingénieur (ED SPI 072)

**Equipe de recherche, Laboratoire :**

Laboratoire d'Automatique, de Mécanique et d'Informatique Industrielles et Humaines (LAMIH – UMR 8201)

**Influence de la texturation de surface sur la biocompatibilité des implants mammaires. Approches amont et clinique.**

## JURY

### Président

- LeHouerou, Vincent. Pr, Head of International Master on Polymer Science (IMPolyS). Laboratory ICube UMR 7357, Strasbourg.

### Rapporteurs

- Amédée, Joëlle. DR1 INSERM, Bioingénierie Tissulaire (BioTis). Inserm U1026, Bordeaux.

- Mazeran, Pierre-Emmanuel. MCF HDR, Enseignant-Chercheur. Laboratory Roberval, FRE CNRS 2012, Compiègne.

### Examinateurs

- Bosc, Romain. MCU, Praticien Hospitalier. Service de Chirurgie Plastique, Reconstructrice, Esthétique et Maxillofaciale, Hôpital Henri Mondor, Créteil.

- Brigaud, Isabelle. IR. Laboratory IS2M, Mulhouse.

- Vayron, Romain. MCF. Laboratory LAMIH, Valenciennes.
## Co-directeurs de thèse

- Anselme, Karine. DR1 CNRS. Laboratory IS2M, Mulhouse.

- Bigerelle, Maxence. Pr, Head of Department of Mechanical Engineering. Laboratory LAMIH, Valenciennes.

## Membre invité

- Gomes, Christophe. Scientific Director Groupe Sebbin, Boissy-l'Aillerie.
# Contents

LIST OF ABBREVIATIONS 5

ACKNOWLEDGEMENTS 6

LIST OF FIGURES 7

LIST OF TABLES 9

GENERAL INTRODUCTION 11

CHAPTER I: INTRODUCTION 15

1.1. HISTORICAL BACKGROUND 15

1.2. BIA-ALCL 22

1.2.1. FDA alert 22

1.2.2. Clinical features 22

1.2.3. Association between breast implant and BIA-ALCL and estimation of a risk 24

1.2.4. Epidemiologic barriers 26

1.2.5. Epidemiologic methodologies to rationalize the risk analysis 29

1.2.6. First BIA-ALCL related epidemiologic structures 30

1.2.7. First recommendations from national regulatory agencies 38

1.3. BREAST IMPLANT SURFACE PROCESS, MEASUREMENT AND DESCRIPTION 40

1.3.1. Breast implant manufacturing and texture 40

1.3.2. The standards related to breast implant surface measurement 45

1.3.3. Breast implant surface measurements published in the literature 46

1.3.4. Breast implant surface description 49

1.4. NOMENCLATURE AND CLASSIFICATION OF BREAST IMPLANT SURFACE 54

1.5. CLINICAL EVALUATION OF BREAST IMPLANT SURFACE 58

1.5.1. Objectives and general principles of clinical evaluation via literature review 58

1.5.2. Clinical evaluation of a link between some types of textures and the incidence of capsular contracture 60

1.5.3. Clinical evaluation of a potential link between some types of textures and the incidence of BIA-ALCL 80

1.5.4. Clinical evaluation of a potential link between some types of textures and the incidence of late seroma or double capsule 97

1.6. BIOLOGICAL MODELS 98

1.6.1. In vivo models 98

1.6.2. In vitro models 102

1.6.3. Ex vivo models 106

CHAPTER II: MEASUREMENT INSTRUMENT AND MULTI-SCALE ANALYSIS 115

2.1. MULTI-SCALE ANALYSIS 116

2.2. MEASUREMENT AND FIRST ANALYSIS OF BREAST IMPLANT SURFACE WITH SEM AND 3D RECONSTRUCTION SOFTWARE 129
<table>
  <tbody>
    <tr>
      <td>2.3. CONCLUSIONS</td>
      <td>132</td>
    </tr>
    <tr>
      <td>CHAPTER III: BIOLOGICAL RELEVANCE OF THE PROPOSED CLASSIFICATION</td>
      <td>135</td>
    </tr>
    <tr>
      <td>3.1 INTRODUCTION</td>
      <td>135</td>
    </tr>
    <tr>
      <td>3.2 ARTICLE</td>
      <td>136</td>
    </tr>
    <tr>
      <td>3.3 OUTLOOK</td>
      <td>179</td>
    </tr>
    <tr>
      <td>CHAPTER IV: TOPOGRAPHICAL RELEVANCE OF THE PROPOSED CLASSIFICATION</td>
      <td>181</td>
    </tr>
    <tr>
      <td>4.1. INTRODUCTION</td>
      <td>181</td>
    </tr>
    <tr>
      <td>4.2. METHODOLOGY</td>
      <td>184</td>
    </tr>
    <tr>
      <td>4.3. RESULTS</td>
      <td>187</td>
    </tr>
    <tr>
      <td>4.3.1. One variable discriminant analyses</td>
      <td>187</td>
    </tr>
    <tr>
      <td>4.3.2. Two variables discriminant analyses</td>
      <td>191</td>
    </tr>
    <tr>
      <td>4.3. DISCUSSION</td>
      <td>193</td>
    </tr>
    <tr>
      <td>4.4 CONCLUSIONS</td>
      <td>199</td>
    </tr>
    <tr>
      <td>CHAPTER V: IN VIVO DAMAGES OF DIFFERENT TEXTURED BREAST IMPLANTS</td>
      <td>201</td>
    </tr>
    <tr>
      <td>5.1 INTRODUCTION</td>
      <td>201</td>
    </tr>
    <tr>
      <td>5.2 MATERIALS & METHODS</td>
      <td>204</td>
    </tr>
    <tr>
      <td>5.3 RESULTS</td>
      <td>208</td>
    </tr>
    <tr>
      <td>5.3.1 Cereform texture (Cereplas) (PV)</td>
      <td>209</td>
    </tr>
    <tr>
      <td>5.3.2 Sebbin round implant texture (Sebbin) (OC)</td>
      <td>211</td>
    </tr>
    <tr>
      <td>5.3.3 Cristalline Micro-texture (Eurosilicone) (OC)</td>
      <td>213</td>
    </tr>
    <tr>
      <td>5.3.4 Nagotex texture (Nagor) (OC)</td>
      <td>215</td>
    </tr>
    <tr>
      <td>5.3.5 Sebbin shaped implant texture (Sebbin) (SOC)</td>
      <td>217</td>
    </tr>
    <tr>
      <td>5.3.6 Biocell texture (Allergan) (SOC)</td>
      <td>219</td>
    </tr>
    <tr>
      <td>5.4 DISCUSSION</td>
      <td>220</td>
    </tr>
    <tr>
      <td>5.4.1 Validation of the breast implant classification</td>
      <td>220</td>
    </tr>
    <tr>
      <td>5.4.2 The transfer function of the implant / explant roughness</td>
      <td>222</td>
    </tr>
    <tr>
      <td>5.4.3 Damage of PV structure</td>
      <td>223</td>
    </tr>
    <tr>
      <td>5.4.4 Damage of OC and SOC structures</td>
      <td>225</td>
    </tr>
    <tr>
      <td>5.5 CONCLUSION AND OUTLOOK</td>
      <td>232</td>
    </tr>
    <tr>
      <td>CHAPTER VI: GENERAL CONCLUSIONS AND OUTLOOK</td>
      <td>235</td>
    </tr>
    <tr>
      <td>6.1 GENERAL CONCLUSIONS</td>
      <td>235</td>
    </tr>
    <tr>
      <td>6.2 OUTLOOK</td>
      <td>237</td>
    </tr>
    <tr>
      <td>APPENDIX 1: Comparative bibliometric study on Hip and Breast Implants</td>
      <td>239</td>
    </tr>
    <tr>
      <td>APPENDIX 2: Multi-scale skewness analysis for SOC-patterned prostheses</td>
      <td>241</td>
    </tr>
    <tr>
      <td>REFERENCES</td>
      <td>243</td>
    </tr>
    <tr>
      <td>THESIS SUMMARY</td>
      <td>255</td>
    </tr>
    <tr>
      <td>RESUME DE THESE</td>
      <td>255</td>
    </tr>
  </tbody>
</table>
LIST OF ABBREVIATIONS

2D Two-Dimensional

3D Three-Dimensional

AFM Atomic Force Microscopy

ANOVA Analysis of Variance

ANSM Agence Nationale de Sécurité du Médicament et des produits de santé

BIA-ALCL Breast Implant-Associated Anaplastic Large Cell Lymphoma

CE Conformité Européenne

DNA Deoxyribonucleic Acid

ECM Extra-Cellular Matrix

FDA Food and Drug Administration

HP High-Pass

ISO International Organization for Standardization

IL Interleukin

LP Low-Pass

MMP Matrix Metalloproteinase

OC Open Cavities

PCA Principal Component Analysis

PCR Polymerase Chain Reaction

PDMS PolyDiMethylSiloxane

PIP Poly Implant Prothese

PU Polyurethane

PV Pics and Valleys

qRT-PCR Quantitative Reverse-Transcriptase Polymerase Chain Reaction

RNA Ribonucleic Acid

SAA1 Serum Amyloid A

SEM Scanning Electron Microscope

SOC Semi-Open Cavities

TIMP Tissue Inhibitor of Metalloproteinase

TGF Tumor Growth Factor

TNFSF11 Tumor Necrosis Factor ligand Superfamily member
ACKNOWLEDGEMENTS

I would like to express my deepest gratitude to my thesis supervisors, Dr. Karine Anselme, and Pr. Maxence Bigerelle, for their support, patience, enthusiastic guidance, valuable suggestions, advices, and constructive criticisms as well as for their expertise and scientific curiosity conveyed throughout the thesis. Their great interest in the thesis was for me the major driving force to complete the thesis.

I also wish to greatly thank Dr. Isabelle Brigaud for her considerable help provided especially during the biological part of the thesis. I also wish to express my sincere gratitude to Dr. Romain Vayron for his writing skills and his relevant analyses and to Dr. Raphael Deltombe and Dr. Rémi Delille for their technical expertise.

I would like to express my warmest thanks to Christophe Gomes for having trust in me and for his confidence. My acknowledgements are also due to Dr. Marie Chiganne for her support and her constant encouragement during the thesis.

I also would like to extend my deep thank to Dr. Nathalie Bricout and Dr. Romain Bosc for their clinical expertise and for their collaboration in the study.

This thesis was conducted as part of a CIFRE (Conventions Industrielles de Formation par la Recherche) contract between the LAMIH laboratory of the UPHF, the IS2M laboratory of the UHA and the GROUPE SEBBIN. I would like to deeply thank the LAMIH laboratory and the IS2M laboratory to have welcomed me. I wish to gratefully acknowledge the financial support provided by GROUPE SEBBIN and all my colleagues and other doctorate candidates for their interest in my work, their sympathy and the friendships forged.

Last but not least, I want to express my sincere appreciation to Dr. Joëlle Amédée et Dr. Pierre-Emmanuel Mazeran to have accepted to read this manuscript and to give their feedback.

To my family and friends.
<table>
  <tbody>
    <tr>
      <td>computed on measured surfaces, i.e. on m(param*)_LP_8. Identification of 4 categories of implant types corresponding to the 4 differently-colored areas on the Sa-distribution.</td>
      <td>198</td>
    </tr>
    <tr>
      <td>Figure 16: Micrometric particles observed in the capsule. (SEM x7500) (Danino et al.)</td>
      <td>201</td>
    </tr>
    <tr>
      <td>Figure 17: Principle of surface filtering (example given with a threshold of 105µm). (A) Measured surfaces containing the full range of roughness scales, once filtered by a High-Pass (HP) filter, retain the roughness scales below the threshold value and up to the instrument resolution. (B) Low-Pass filter (LP) filtered surfaces only contain roughness scales above the threshold value.</td>
      <td>207</td>
    </tr>
    <tr>
      <td>Figure 18: Multi-scale curves of Sa<sub>implant</sub> and Sa<sub>explant</sub> and F for Cereform texture (PV)</td>
      <td>209</td>
    </tr>
    <tr>
      <td>Figure 19: "Smoothing" of micro-roughness on Cereform explants (left: implant, right: explant)</td>
      <td>210</td>
    </tr>
    <tr>
      <td>Figure 20: Multi-scale curves of Sa<sub>implant</sub> and Sa<sub>explant</sub> and F for Sebbin round implant texture (OC)</td>
      <td>211</td>
    </tr>
    <tr>
      <td>Figure 21: Damage on Sebbin round textured explants (left: implant, right: explant)</td>
      <td>212</td>
    </tr>
    <tr>
      <td>Figure 22: Multi-scale curves of Sa<sub>implant</sub> and Sa<sub>explant</sub> and F for Eurosilicone Cristalline Micro-texture (OC)</td>
      <td>213</td>
    </tr>
    <tr>
      <td>Figure 23: Appearance of very small irregularities on the Eurosilicone Cristalline Micro-texture explant (left: implant, right: explant)</td>
      <td>214</td>
    </tr>
    <tr>
      <td>Figure 24: Multi-scale curves of Sa<sub>implant</sub> and Sa<sub>explant</sub> and F for Nagotex texture (OC)</td>
      <td>215</td>
    </tr>
    <tr>
      <td>Figure 25: Macroscopic irregularity of the cavities on the Nagor explant (left: implant, right: explant)</td>
      <td>216</td>
    </tr>
    <tr>
      <td>Figure 26: Multi-scale curves of Sa<sub>implant</sub> and Sa<sub>explant</sub> and F for Sebbin shaped implant texture (SOC)</td>
      <td>217</td>
    </tr>
    <tr>
      <td>Figure 27: Macroscopic opening of cavities on the explants (left: implant, right: explant)</td>
      <td>218</td>
    </tr>
    <tr>
      <td>Figure 28: Multi-scale curves of Sa<sub>implant</sub> and Sa<sub>explant</sub> and F for Biocell texture (Allergan)</td>
      <td>219</td>
    </tr>
    <tr>
      <td>Figure 29: Large heterogeneity of Allergan explant surface (left: implant, right: explant)</td>
      <td>220</td>
    </tr>
    <tr>
      <td>Figure 30: Classification of implants obtained by discriminative analysis (left) and projection of our explants database on this classification (right)</td>
      <td>222</td>
    </tr>
    <tr>
      <td>Figure 31: Identification of the damage regimes of the different categories of texture and associated topographical characteristics</td>
      <td>223</td>
    </tr>
    <tr>
      <td>Figure 32: 2-D damage modelling of the debris mill mechanism on a PV implant</td>
      <td>225</td>
    </tr>
    <tr>
      <td>Figure 33: Appearance of microscopic irregularities within cavities of the Sebbin shaped explants</td>
      <td>227</td>
    </tr>
    <tr>
      <td>Figure 34: 2-D damage modelling of the damage mechanisms on an OC implant</td>
      <td>228</td>
    </tr>
    <tr>
      <td>Figure 35: 2-D damage modelling of the damage mechanisms on a SOC implant</td>
      <td>228</td>
    </tr>
    <tr>
      <td>Figure 36: Schematic representation of the bias, which will appear on the Sa values during the opening of SOC structures</td>
      <td>230</td>
    </tr>
    <tr>
      <td>Figure 37: The Sa evolution computed on the topographies measured (i.e. before multi-scale analysis) according to the implant duration</td>
      <td>231</td>
    </tr>
    <tr>
      <td>Figure 38: OC explant's undulation characteristic of a "heterogenous stress relaxation"</td>
      <td>232</td>
    </tr>
  </tbody>
</table>
LIST OF TABLES

Table 1: Worldwide and nation-wide numbers of BIA-ALCL cases and related deaths as of November 2018. 28

Table 2: Clinical data related to BIA-ALCL published by the newly established registries and regulatory agencies in the French- or English-speaking countries in the world 37

Table 3: Textures of the major breast implant manufacturers and associated texturing processes 44

Table 4: Topographical measurements and characterizations published in the literature 48

Table 5: Morphological descriptions of the textures in the literature 52

Table 6: Classifications of the different breast implant surfaces according to the published nomenclatures 57

Table 7: Search implemented on the scientific databases 66

Table 8: Selected and non-selected articles through the scientific database search 77

Table 9: Cumulative risks of capsular contracture of different breast implant surfaces retrieved from the scientific database search 79

Table 10: Selected and non-selected articles through scientific database search 86

Table 11: BIA-ALCL cases per manufacturer reported by the French regulatory agency (ANSM) and by the Canadian regulatory agency (Health Canada) 87

Table 12: BIA-ALCL cases per type of breast implant surface reported by the LYMPHOPATH network 88

Table 13: BIA-ALCL cases per type of breast implant surface and hypotheses of pathogenesis retrieved from scientific and federal database search 96

Table 14: Comparison of the 4 existing classifications (in color the implants analyzed in our classification: SMOOTH, PV, OC and SOC) 196

Table 15: Implant characteristics and patient clinical data of the explant sampling. For clarity, the color height scale for the PV category was not represented. The approximate maximal height of this type of structure is 100µm. 206

Table 16: Determination of categories of the breast implant classification 221

Table 17: Difference between the Sa<sub>explant</sub> and the Sa<sub>implant</sub> (or Delta) for each texture at a scale of 10µm. 227
The first surface patterning of breast implants (also called textures) only appeared in 1987. It was designed to reproduce the "immobilizing" effect of implants covered with Polyurethane (PU) foam, whose safety began to become controversial. This propensity to anchor into surrounding biological tissues has become essential for the 5th generation implants, also known as "form stable implants". Indeed, the stability of these implants, which are anatomically shaped, in the breast must be perfect to avoid disastrous aesthetic results.

Under pressure from the media, which warned patients against the paucity of the
information provided by the manufacturers on the biologic profile of silicone, the
American Health agency Food and Drug Administration (FDA) imposed in 1992 a
moratorium on implants filled with silicone gel, allowing then in the US territory only
inflatable implants filled with saline. From now on, to market breast implants in the US,
manufacturers will need to provide safety for their device through large-scale clinical
studies (called "Core Studies"). Once the scientific evidence of the safety of the
silicone was published, the moratorium was lifted in 2006. Simultaneously, breast
implants became class III medical devices.

The biological mechanisms responsible for integrating the implant into the body are
beginning to be better understood. Thus, because of the foreign body reaction, any
breast prosthesis once implanted is surrounded by a fibrous capsule. In some cases,
this capsule may thicken and harden, causing pain in the patient. This is capsular
contracture.

After a first reading of these clinical studies, a reducing effect of the capsular
contracture rate of the textured implants compared to the smooth implants was
thought. Motivated by all these clinical benefits (which are supposed to be), all the
manufacturers started to develop implant textures. The rougher ones have been
called "macrostructures", while the less rough ones have been called "microstructures".
These arbitrary designations only respond to marketing logic on the part of
manufacturers. They have neither clinical sense nor topographical sense. Therefore, it
was difficult because of the non-standardization of these clinical studies, to
demonstrate the clinical benefit (for example in terms of reducing the risk of capsular
contracture) of such type of texture compared to another type of texture.

Ten years after the commercialization of textured implants, a new pathology was
identified on a woman carrying breast implants. It is a lymphoma presenting particular
characteristics, such as the confinement of the pathology to the fibrous capsule. It was
only after a publication in 2015 reporting an exponential increase in cases of this
lymphoma and an over-representation of Allergan's Biocell texture in statistics, that
Health authorities were beginning to worry about this pathology and the link between
certain types of textures and the risk of lymphoma. In 2017, the World Health
Organization (WHO) introduced a new category for this pathology in its lymphoma
classification: Breast Implant-Associated Anaplastic Large Cell Lymphoma (BIA-ALCL).
With the establishment of specific registries in some countries and clinicians'
awareness, BIA-ALCL's first incidence estimates did literally explode. They increased
from 1 in 500,000 in 2015 to 1 in 3,000 in 2016. An Australian study even determined that
depending on the type of texture, the risk of BIA-ALCL could vary from 1 in 3,000 to 1
in 60,000. At present, such a study could not be conducted in other countries, due to
registries that are not sufficiently mature to provide robust clinical data or to
manufacturers reluctant to provide sales figures.

BIA-ALCL is acknowledged to be a result of chronic inflammation of the surrounding
tissues. However, the origin of the inflammation remains to be identified. Various
hypotheses were proposed in the literature, such as the biofilm that would develop on
the surface of prostheses once implanted or the release into the tissue of silicone debris
from the surface.

For the reasons previously mentioned, the paucity of data precludes a demonstration
of the clinical impact of certain types of texture. Nevertheless, on the basis of the
above hypotheses, the impact of the textures on the biocompatibility of the implant
was analysed thereafter. As the propensity of certain surface patterns to develop a
biofilm has been widely studied in the literature, this hypothesis will not be studied in
our investigations. However, the influence of the implant topography on tissue
inflammation or potential post-implantation surface damage will be analyzed and will
allow us to assess the relevance of these hypotheses for the pathogenesis of BIA-ALCL.
Before correlating certain implant textures with biological or post mortem
characteristics, the surfaces had to be measured according to an appropriate
protocol, in terms of instrument, objective and resolution. Once the surface
topographies were measured and the metrological parameters calculated, different
measuring instruments were compared on 4 different types of implant surfaces via the
multi-scale analysis. This was published in Surface Topography: Materials and
Properties. This work allowed us to criticize the new version of the International
Organization for Standardization (ISO) standard for breast implants (ISO 14607)
released in 2018.

On the basis of the morphologies observed on the topographies, a classification of the
textures was proposed. This classification allowed us to determine whether the
topography (and more specifically the identified morphologies) has an impact on the
molecular mechanisms occurring in the surrounding biological tissues. Previous
transcriptomic studies have identified a number of relevant genes for an
asymptomatic capsule / pathological capsule comparison. Based on this selection of
genes and by restricting our study to healthy capsules, we were able to determine
whether these different surface textures elicit a specific molecular response, including
a particular inflammatory response. In view of the clinical complications (in particular
capsular contracture), we considered relevant to integrate in the analysis some
markers of the synthesis / degradation of the Extra-Cellular Matrix (ECM) (which
constitutes the capsule). This study was the subject of an article that was accepted on
03/07/2019 for publication in the journal Plastic and Reconstructive Surgery.

Contrary to the existing nomenclatures in the literature, a statistical analysis was able
to select the couple of topographical parameters and the spatial scale on which our
classification is based and to demonstrate their robustness. This analysis will allow us to
demonstrate putative correlations between the topographical characteristics and the
obtained biological profile. This study will be the subject of an article that will be
submitted for publication soon.
Before concluding on the biocompatibility of breast implants (or of any implantable device), it is fundamental to carry out tribological tests or to evaluate the potential damage to the surface of a prosthesis once implanted (or explant). Such studies on breast implants do not exist in the literature. We therefore compared at different scales the damage of 6 different explant textures. As part of this first ex vitro study, damage regimes were identified for each category of our classification. For each of these regimes, mechanisms of wear have also been suggested. This study was the subject of an article that will be submitted for publication soon.
1.1. HISTORICAL BACKGROUND

The history of breast implant spreads over the last 50 years. Numerous attempts were
led, before the development of breast implant, we know nowadays. Often the new
designs introduced by the companies were conceived by individual surgeons. This
history is sometimes confusing because many of the suppliers or manufacturers
changed their names and ownership over the years.

A first attempt of implant-based breast augmentation based on implantation of a
glass ball was performed in the 1930s by Schwarzmann and will be used until 1942. (1)
Then, development of breast implant design with new polymer materials was led from
1951 to 1962. The implant was then a synthetic sponge. Thus, 3 chemically different
sponges were developed: Ivalon (a polyvinyl alcohol sponge), Etheron (a polyether
sponge) and Polystan (composed of fabric tapes that were cut and then wound into
a ball). Dr William John Pangman formed Poly-Plastic Company to manufacture his
own brand of Ivalon implants. In 1961, approximately 16 600 Ivalon implants had been
inserted. The results were poor and sometimes disastrous (the breasts became firm and
lost over 25% of their volume). (2)

In 1962, under the leadership of Dow Corning Company, two surgeons from Houston (Texas, USA), Frank Gerow and Thomas Cronin designed the first modern breast implant formed of an "anatomically" shaped (teardrop) envelope and filled with moderately viscous silicone gel. The shell of the **first-generation implants** was designed with a 0.75mm thick, smooth silicone elastomer as a 2-piece envelope with a seam along the periphery. (3) A single roughened Dacron (polyethylene terephthalate) patches was added on the posterior side of the implant to promote tissue adhesion and to avoid prosthesis displacement. (4) In 1964, 4-quadrant patches were used. In 1968, 3, 4 or 5 patches could be fixed, depending on the implant volume. (2)
This new prosthesis was marketed in the US in 1964 and was an immediate success. Dow Corning had an almost exclusive monopoly on their manufacture. From 1969 onward, all shells were seamless. However, several drawbacks were quickly reported:

* Large scar on the breast skin due to the long submammary incision required for this type of implant

* Sagging of the breast downward (or ptosis) due to the Dacron patches fixing only the posterior face of the prosthesis to the chest wall behind the gland.

Moreover, the periprosthetic capsule surrounding the implant was often too thick and contractile, resulting in a firm, hard and sometimes even distorted breast (1, 4, 5). This complication was firstly named "fibrous envelope contracture" by Freeman in 1972 (6) and will be then called "capsular contracture", which will be the most significant clinical adverse event associated with breast implant throughout the next decades.

At the same moment, in 1965 the use of inflatable saline filled implant was reported for the first time by Dr Henri Arion, in France. The implant was constituted of a 0.35mm thick elastomeric shell with a peripheral circumferential seam, a filling tube and a valve attached permanently to one side. Different companies marketed inflatable saline filled implants: Simaplast in France, Heyer-Schulte (which manufactured in the USA in 1968 the "Jenny implant") and Dow Corning (from 1970). Different silicone types were used thereafter: High Temperature Vulcanization (HTV) silicone and then Room Temperature Vulcanization (RTV) silicone. (2)

In 1968, Drs Franklin Ashley and William John Pangman developed a 1.2-2 mm polyurethane (PU) foam-coated and gel-filled implant manufactured by Polyplastic Silicone Products (PSP): the "Ashley Natural Y Implant". An inverted Y-shaped internal divider was designed to maintain the shape of the implant by preventing the gel from sagging to the deep part of the implant. (7) In 1971, Heyer-Schulte acquired the rights for the Ashley Natural Y Implants from PSP. Surprisingly, the subglandular rate of capsular contracture was drastically reduced (3.3%) compared to the existing implants. (8) Consistently, Vazquez observed a different collagenous and presumably less contractible capsule architecture around PU-coated implants. (9)
The **second-generation** implant developed in the 1970s was made of round implants with a smooth, thinner (0.13mm) and seamless shell and without Dacron patches incorporated into the shell. These implants were filled with a less viscous silicone gel than the first-generation implants. Softer implants were therefore designed with the idea that they would result in softer breasts. Although the incidence of capsular contracture was reduced, diffusion or bleed of short chains of polymeric molecules contained in the gel throughout the shell, as well as shell ruptures, were more frequent. (1, 4, 5) In 1972, Heyer-Schulte and Medical Engineering Corporation (which later became Surgitek) began to market gel-filled implants in the USA. Then, McGhan introduced its first gel-filled breast implant in 1974.

The **third generation** of smooth silicone implants, developed in the early to mid-1980s, aimed at improving the strength and permeability of the silicone shell. This generation of implants was characterized by thicker (0.30 to 0.50mm) and multi-layered shells containing a chemically different layer called "barrier". This envelope design considerably reduced gel bleed and device shell failure rate. (1, 4, 5) McGhan started to market its 3rd generation implant in the USA in 1979. The implant Silastic II was introduced by Dow Corning in the USA in 1981. Then, Surgitek Strong, Cohesive, Low-bleed (SCL) implants appeared in the USA in 1986. As a low-bleed barrier, Surgitek and McGhan incorporated within the shell a diphenyl layer, whereas Dow Corning used a 0.010mm coating of fluorosilicone on the interior surface of the shell.

As at that time the low capsular contracture profile was attributed to the PU coating, the other manufacturers then decided to imitate this type of surface structure. In 1987, all PU-coated implant brands were acquired by Cooper Laboratories and then by Surgitek in 1988. Thus, new surface processing had to be developed by the other manufacturers. The first development to make the envelope irregular and "textured" appeared in the 4th generation of implant. The first FDA-approved texture was in 1987 the Biocell texture commercialized by McGhan (which will become later Inamed then Allergan in 2006), then Mentor Siltex® 2600 manufactured by Biomedic-Mentor was approved in 1988. In 1989, Dow Corning developed its Micro Structured Implants (MSI),
whose the surface exhibited regular pillars 250µm in diameter, 750µm high and 500µm apart. Two cross-sections of this surface pattern are exhibited in the Figure 1. (2)

<figure><img src="image_3.png" /><figcaption>Figure 1: Cross-sections of the MSI surface pattern observed by SEM (A: magnification x65, B: magnification x150) (Peters et al.)</figcaption></figure>

An enormous public pressure fuelled by unions of patients and lawyers exploded in the USA in 1990, consequently to articles in the press and talk shows, which warned patients against the paucity of the information provided by the manufacturers on the biologic profile of silicone. A few years later, the largest class action lawsuit in medical history broke out in the United States. In 1993, the Dow Corning Company was facing bankrupt because of 12 359 patient complaints. David Kessler (Head of FDA) established a "voluntary moratorium" on the distribution and implantation of silicone
breast implants in the USA in January 1992, only on the basis of inadequate demonstration of biocompatibility provided by the manufacturers. A month later, the "General and Plastic Surgery Devices Panel" recommended reserving silicone gel-filled implants for breast reconstruction and for teams following a rigorous scientific protocol. (4) High quality scientific researches then demonstrated no increased risk of connective tissue diseases (10-12), of neurologic disorders (13) and of any cancer (14) in women with silicone implants. The suspension was lifted in 2006, with the approval of Mentor and Allergan silicone gel-filled implants. (15)

Since the first US medical device regulations in 1976, breast implants were "grandfathered" as a Class II medical device. (16) In 1988 the FDA under pressure upgraded the breast implants as a Class III higher risk medical device. Strict premarket clinical studies were then required to be approved by the FDA. (1) A consequence of the moratorium is a shift of the Northern American implant market. From 1963 to 1992, approximately 95% of implants were silicone gel-filled. Then, since the moratorium, 95% have been saline filled. (2)

The European regulatory agencies began to restrict access to silicone gel-filled breast implants in June 1993. The European Commission released a Medical Device Directive, which obligated new devices to be certificated by an independent organism. (15) A temporary ban on silicone gel-filled breast implants was even ordered France between 1995 and 2001.

At the same time, the US sales of PU-coated implants were suspended in April 1991 because a hydrolysis of the PU foam (which was shown to release *in vitro* a toxic breakdown product: 2,4-toluenediamine or 2,4-TDA) was thought to occur during the *in vivo* macroscopic degradation of the PU foam. (17) Before 1990, PU-coated implants represented 40% of the implant market. (18) The hypothesis of toxicity was ruled out later by subsequent reports: the very small amounts of 2,4-TDA that would be released from PU-coated implants would not provide a significant health risk. (19)

In the years following the lifting of the moratorium, a 5th generation appeared. Thanks to more cohesive gels, the concept of "form-stable" implant was achieved. Thus,
anatomically-shaped implants (tear drop) were designed. (1, 4, 5) The same surface processing designed for round implants (such as Siltex and Biocell) continued to be used for most shaped implants. (Fig. 2) On the basis of the provided clinical data, the FDA approved fifth-generation implants from all the US suppliers in the following order: Sientra (the US supplier of Silimed implants) (2012), Allergan (acquired by Actavis in 2014) (2013), and Mentor (acquired by Johnson & Johnson in 2009) (2013).

<figure><img src="image_4.png" /><figcaption>Figure 2: SEM images of Silimed TRUE Texture, Mentor Siltex and Allergan Biocell textured surfaces. (magnification: x65) (20)</figcaption></figure>

More recently, a new type of texturing process (called “microtexture” or even “nanotexture”), which uses no foreign material, is appeared. The “microtexture” of PERTHESE implant (Perouse Plastie) was the first of this type reported in the literature. (21)
The first breast reconstruction after cancer was published in 1979 and 1982 and relied on the insertion of temporary expander after the resection of tumorous tissue (mastectomy). (22, 23) Specific expanders (textured or smooth) for breast reconstruction were then designed. Once implanted, the expander is progressively filled with saline solution through a valve over a period of approximately 6 months. (24) Once the breast tissues are sufficiently distended, the expander is replaced by a definitive implant. (25) A partial resection of the capsule (capsulectomy) is also performed. Nowadays, other options exist for breast reconstruction, such as flap or lipofilling procedures. These autologous techniques consist in harvesting a section of tissue (either muscular tissue for a flap or adipose tissue for a lipofilling) from one area of the body — most often the abdomen — and relocating it to create a new breast mound).

In the last past decades, several medical controversies shadowed breast implants. The most known crisis is the suspension of exportation, distribution and sale of the Poly Implant Prothèse (PIP) silicone gel-filled breast implants in March 2010, consequently to a fraud of the manufacturer on the silicone supply. More than 300 000 women in 65 countries have received PIP silicone gel-filled implants made with nonmedical-grade silicone. (26) In September 2015, the Conformité Européenne (CE) certificate of the Silimed implants was suspended due to the discovery of particulate on device surface. In October, Sientra voluntary suspended the sales of Silimed implants in the USA as a precaution. (15) However, the most publicized implant-related health topic, who concerned several worldwide health authority agencies, is an emerging risk of a rare type of cancer affecting immune systems (Breast Implant-Associated Anaplastic Large Cell Lymphoma or BIA-ALCL), which would be linked to breast implant. In December 2018, Allergan lost the CE mark on Microcell- and Biocell-textured implants for reasons explained below in §1.2.7. (27)
### 1.2.1. FDA ALERT

Since the safety warning issued by the FDA in 2011 on a possible association between breast implant and BIA-ALCL (https://www.fda.gov/news-events/press-announcements/statement-binita-ashar-md-fdas-center-devices-and-radiological-health-agencys-continuing-efforts), an increasing attention, which is now beyond the communities of breast surgeons and haematologists, was paid on this pathology.

At that time, 34 BIA-ALCL case reports were known worldwide. (28) Without any more additional epidemiologic data, they estimated the incidence of primary ALCL of the breast to be approximately three in 100 million women per year in the United States, based on data from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute. (29)

According to this report, women with breast implants would have a very low but higher risk of developing an BIA-ALCL compared to women without breast implants, although cases of lymphoma similar to ALCL have been reported without association with breast implants. (30-33) The first case was identified in the USA in 1997 by Keech. (34) However, the number of newly diagnosed patients exploded in 2014-2015. (35) In 2017, a specific entity was created in the revised World Health Organization (WHO) classification of lymphoma under the terminology "BIA-ALCL". (36)

### 1.2.2. CLINICAL FEATURES

ALCLs are a proliferative disorder affecting lymphoid (or immune) cells. Different clinicopathological forms of ALCL exist: systemic ALCL, cutaneous ALCL and BIA-ALCL. While systemic ALCL is an aggressive metastatic disease, malignant lymphoid cells of BIA-ALCL are usually confined to a peri-implant seroma or capsular tissue. (37, 38) BIA-ALCL is a rare and purely T-cell lymphoma. (39, 40) A characteristic genetic subtyping of BIA-ALCL appeared: all currently reported cases were found to be anaplastic lymphoma kinase negative (ALK-) with cluster of differentiation 30 positive (CD30+). (41) Cutaneous ALCL also shows ALK- and CD30+. (42)
Clinically, approximately two thirds of BIA-ALCL cases were diagnosed consequently to breast swelling due to an effusion around the implant. This seroma fluid contained malignant cells, especially the characteristic large pleomorphic cells with horseshoe-shaped nuclei. (43) About one third of BIA-ALCL cases were characterized by a tumor mass attached to the capsule, usually perceptible by the patient. An effusion may also be observed. Metastatic disease was observed on a very small number of patients. (41, 44)

The time interval from implantation to diagnosis ranges from 2 years to 32 years with a median interval of 8-9 years. BIA-ALCL was diagnosed on both augmentation and reconstruction patients. (44) Potential ethnic and genetic predispositions may play an important role (45), with only one worldwide Asian or Asian descent case from Thailand (46). Thus, genetic aberrancies were observed in BIA-ALCL cases. Somatic mutations in JAK-STAT signalling, which are implicated in cell proliferation, differentiation and apoptosis, were the most commonly reported aberrancies. (47-50)

In term of first-line diagnosis tool, ultrasound techniques were found as specific and sensitive as more invasive techniques. (51) On suspected cases, tissue specimens should be harvested via fine-needle aspiration or biopsy for pathological examination. (41) The first National Comprehensive Cancer Network consensus guidelines for the management of BIA-ALCL developed in 2016 recommended that specimens undergo histology, flow cytometry and immunohistochemistry. The CD30 markers should be then systematically scored. (52)

BIA-ALCL as well as cutaneous ALCL are associated with a relatively slow rate of progression and a generally favourable prognosis. (42) Complete remission was reported in 93% of BIA-ALCL cases with effusion in the absence of a mass and in 72% of cases if a mass was also present. The therapy is most of the time based on a complete resection of the capsule with removal of implants. (38) Anecdotal case reports of spontaneous regression on effusion-limited BIA-ALCL patients have now been published. (53, 54)
1.2.3. **ASSOCIATION BETWEEN BREAST IMPLANT AND BIA-ALCL AND ESTIMATION OF A**
RISK

Methodologically, to assess the efficiency of a treatment against a given pathology, a case control study must be performed. A matched control group must therefore be enrolled. This type of study is also designed to demonstrate a putative association between breast implants and BIA-ALCL. The association is quantified by the odds ratio (OR), which will indicate in one situation how many times the probability is higher that a patient diagnosed with BIA-ALCL has breast implants than no breast implant. The study design and the details of the computation are detailed in the following paragraphs.

On the basis of 5 cases identified in the Netherlands in 2008, De Jong et al. was the first through a case control study to demonstrate that patients with BIA-ALCL were significantly more likely to have breast implants. (55) The authors also computed an incidence estimated at 0.1 to 0.3 per 100 000 women with breast implant per year. However, they acknowledged "uncertain data of sales figure". Curiously, the cases reported occurred on saline-filled implants, which were infrequently used in Europe.

In 2012, Largent et al. reviewed prospectively 6 clinical studies sponsored by Allergan to encompass 89 382 patients. (56) Three BIA-ALCL were diagnosed. Thus, the authors reported a crude incidence of 1.46 per 100 000 person-years from a clinical study with a median follow-up of 2.7 years

In 2015, by an extensive review of 173 cases retrieved from the literature, Brody et al. estimated an extremely large risk range from 1 in 500 000 to 1 in 3 000 000 women with implants from 1993 to June 1, 2014. (35)

In August 2016, Wang et al. reported 10 cases of BIA-ALCL on a database of 123 392 women (whose 2 990 women had breast implants). (57) Of these 10 cases, 2 patients had breast implants. The authors demonstrated a statistically significant association between breast implant and BIA-ALCL (the risk for BIA-ALCL was increased 10.9 times in patients who had a history of breast implant).

In September 2016, the French National Cancer Institute (INCa) reported 29 cases of BIA-ALCL. On the basis of a large number of assumptions, the experts computed a cumulative incidence of BIA-ALCL of approximately 1 to 2 per 100 000 person-years, which is consistent with the review led by Largent.
In November 2016, Doren et al. retrospectively analyzed 100 BIA-ALCL cases in the USA. (58) Based on the annualized sales data provided by the manufacturers, they estimated an incidence of 2.03 per 1 million person-years, similar to the Dutch study. Moreover, this incidence was 67.6 times higher than that of primary ALCL of the breast in the general population, according to the SEER data (p<0.001). The authors assessed the lifetime prevalence (which is the ALCL risk that a woman with breast implants has throughout her entire life span) at 1 per 30 000 women with a breast implant, which is approximately 10 times higher than the rate provided by Clemens et al. (46) Importantly, the authors assumed that BIA-ALCL occurs only on patients with textured implants.

The European Commission-mandated Scientific Committee on Health Environmental and Emerging Risks (SCHEER) released a report in April 2017, which mitigated the possible connection between breast implants and BIA-ALCL on the basis of a review of the published scientific literature and a public call for data open to all stakeholders between 1969 and August 2016 ("the gathered scientific information is insufficient to perform a methodologically robust risk assessment on the positive association of breast implants with the development of ALCL"). (https://ec.europa.eu/health/sites/health/files/scientific_committees/scheer/docs/scheer_o_007.pdf) However, among the 188 articles retained by the literature review, 9 articles concluded a statistically significant positive association between breast implant exposure and risk of BIA-ALCL (51, 55, 56, 59-64), whereas only 2 articles demonstrated a statistically significant negative association according to the experts. Of these two articles, the first one drew conclusion from no identified BIA-ALCL cases on a cohort of 440 patients (65) and the conclusions of the second one were statistically inconclusive (66).

In May 2017, Clemens et al. published outcomes on the US FDA-mandated Continued Access Reconstruction/Revision Expansion (CARE) clinical trials, which are the largest prospective series of patients with textured implants (17 656 women). The authors estimated a lifetime prevalence of 1 in 2943. (46)

In January 2018, a case control study was led on all the breast ALCL and the other primary breast lymphoma declared in the nationwide Dutch pathology registry between 1990 and 2016. (67) The methodologically robust design of a case control
study is based on 4 groups: a group of treated and diseased patients, a group of treated and disease-free patients, a group of untreated and diseased patients and a group of untreated and disease-free patients. In the study, the treatment was the presence of breast implant. The diseased patients were all patients with breast ALCL (n=43) and the disease-free patients (or controls) gathered the women with other primary breast lymphoma (n=146). The number of patients with breast implants were then counted (n=32 among the diseased patients and n=1 among the disease-free patients). The association between breast implant and ALCL is given by the odds ratio (OR):

$$OR = \frac{\frac{32}{43 - 32}}{\frac{1}{146 - 1}} = 421.8 \quad [1]$$

On the basis of this very high OR, the authors updated the outcome given in 2008 (OR was then equal to 18.2) (55) and concluded that "breast implants are associated with increased risk of breast-ALCL, but the absolute risk remains small". Moreover, for the first time the authors took into account the patient age for the prevalence computation. Thus, among women with an implant, the prevalence was estimated of 1 per 35 000 at age 50 years, 1 per 12 000 at 70 years, and 1 per 7 000 at 75 years. The lifetime prevalence provided by Doren et al. was similar as the prevalence at age 50 years, which might be explained by the mean age of Doren study (53.2 years). In comparison, the lifetime prevalence estimated by Clemens et al. was much higher, which is likely due to the unique type of texture represented in the study (i.e. Biocell).

As a result, the determination of an accurate risk has been elusive and a large discrepancy of BIA-ALCL incidence rate has been reported in the literature, which may reflect a combined effect of the increased awareness of this disease among the different stakeholders and geographical predisposition. (68) The following paragraph sheds light on the difficulties to have accurate epidemiologic figures.

### 1.2.4. EPIDEMIOLOGIC BARRIERS

To compute a risk, the number of BIA-ALCL (numerator) and the total number of patients with breast implants (denominator) must be known.
As of November 2018, 656 BIA-ALCL cases and 17 related deaths were reported throughout the world. (69) To have a nation-wide vision, the number of cases and related deaths is given per country in the Table 1. The American Society of Plastic Surgeons (ASPS) estimated 735 worldwide BIA-ALCL cases as of August 5, 2019.

(https://www.plasticsurgery.org/for-medical-professionals/health-policy/bia-alcl-physician-resources)

<table><thead><tr><td>Country</td><td>Cases</td><td>Deaths</td></tr></thead><tbody><tr><td>Argentina</td><td>6</td><td></td></tr><tr><td>Australia</td><td>81</td><td>3</td></tr><tr><td>Belgium</td><td>10</td><td></td></tr><tr><td>Brazil</td><td>3</td><td>1</td></tr><tr><td>Canada</td><td>25</td><td></td></tr><tr><td>Chile</td><td>2</td><td></td></tr><tr><td>China</td><td>0</td><td></td></tr><tr><td>Colombia</td><td>6</td><td></td></tr><tr><td>Czech Republic</td><td>1</td><td></td></tr><tr><td>Denmark</td><td>7</td><td></td></tr><tr><td>Egypt</td><td>1</td><td></td></tr><tr><td>Finland</td><td>7</td><td></td></tr><tr><td>France</td><td>55</td><td>3</td></tr><tr><td>Germany</td><td>7</td><td></td></tr><tr><td>Ireland</td><td>1</td><td></td></tr><tr><td>Israel</td><td>8</td><td></td></tr><tr><td>Italy</td><td>28</td><td></td></tr><tr><td>Japan</td><td>0</td><td></td></tr></tbody></table>
<table><caption>Table 1: Worldwide and nation-wide numbers of BIA-ALCL cases and related deaths as of November 2018.</caption><tr><td>Mexico</td><td>4</td><td></td></tr><tr><td>Netherlands</td><td>40</td><td>1</td></tr><tr><td>New Zealand</td><td>13</td><td>1</td></tr><tr><td>Norway</td><td>3</td><td></td></tr><tr><td>Romania</td><td>0</td><td></td></tr><tr><td>Russia</td><td>2</td><td></td></tr><tr><td>Singapore</td><td>0</td><td></td></tr><tr><td>South Africa</td><td>1</td><td></td></tr><tr><td>South Korea</td><td>1</td><td></td></tr><tr><td>Spain</td><td>29</td><td></td></tr><tr><td>Sweden</td><td>6</td><td>2</td></tr><tr><td>Switzerland</td><td>4</td><td></td></tr><tr><td>Taiwan</td><td>Not reported</td><td>Not reported</td></tr><tr><td>Thailand</td><td>1</td><td></td></tr><tr><td>Venezuela</td><td>2</td><td></td></tr><tr><td>United Kingdom</td><td>45</td><td>1</td></tr><tr><td>United States</td><td>257</td><td>5</td></tr><tr><td>Total</td><td>656</td><td>17</td></tr></table>

According to Collett et al., the numerator is likely to underestimate due to an underreporting of cases in the medical device vigilance database. Basically, any serious incident occurred on a breast implant or on any medical device must be declared to the national Competent Authority, either by the clinicians or the manufacturers. Poor awareness of the disease by the surgeon as well as by the pathologist, fear of litigation or additional cost may be the root cause of these
unreported cases. An overestimation may also skew the figures: Rastogi et al. cautioned against duplicate case reports. (70) The FDA acknowledged that the reporting may contain incomplete, inaccurate, untimely, unverified or biased data. (https://www.youtube.com/watch?v=wpdkXMEj60U)

Regarding the denominator, more than 35 million of women would have textured breast implants in the world, with 1 469 606 and 70 683 breast augmentations performed in 2017 with silicone gel-filled implants and with saline implants respectively. (https://www.isaps.org/wp-content/uploads/2018/10/ISAPS_2017_International_Study_Cosmetic_Procedures.pdf) Based on the sales figures provided by Allergan and Mentor, Doren estimated that approximately 3 millions of women (less than 2% of the total female population) would have textured breast implants in the US population in 2016. In 2017, 281 316 and 41 616 breast augmentations were performed in the USA with silicone gel-filled implants and with saline implants respectively. In the Netherlands, 3.3% of women had textured gel-filled breast implants in 2015. (67)

These figures reflect a globally and sharply increasing breast implant market. The exponential rise in breast implant surgery in Asia and in South Korea more particularly is the best example of this upward trend. (69) However, consistently with the numerator, the estimations of the denominator are inaccurate. Collett et al. detailed the list of factors, which potentially skew the denominator, such as poor records, lack of systematic follow-up and reporting of adverse events, unregulated boom in cosmetic tourism and entry of many disparate practitioners.

To overcome all these biases, it is of prime importance to constitute reliable national and international epidemiologic datasets.

### 1.2.5. EPIDEMIOLOGIC METHODOLOGIES TO RATIONALIZE THE RISK ANALYSIS

Two approaches exist to accurately quantify the denominator. The first one is based on sales data released by manufacturers. De Jong et al. (55) and Doren et al. (58) applied this methodology to compute the provided incidences. However, numerous manufacturer-dependent limitations exist. Sales data may not be accessible because of commercial arguments, logistic changes or bankruptcies. Moreover, it is
not reasonable to assume that the number of implants sold equates to the number
of implants inserted. (69) The second approach relies on radiologic sampling of a
random population. (67) Thus, radiology allows the epidemiologist to confirm the
presence of breast implants. However, this technique is quite time consuming and
requires an extrapolation to upscale the small sample to nation-wide statistics. (69)

Registry is the “gold standard” to accurately estimate the numerator. (69) Basically, adequate registry will be a platform, in which physicians record at least each pathologically confirmed BIA-ALCL case. By extending the input to any breast implantation, registry could be implemented to also provide the denominator. Moreover, by systematically collecting a comprehensive set of critical elements, such as demographic and clinical characteristics of patients, pathologic features, modalities of diagnosis and therapeutic regimens, registry will be a powerful tool to have more insights on the implant-specific risks, on the etiology of BIA-ALCL and on the prognosis. Until now, the implant-specific approaches are plagued by inaccurate implant exposure histories. (70)

National and international registries are now beginning to generate early high-
volume datasets, which are presented in the below paragraphs.

1.2.6. FIRST BIA-ALCL RELATED EPIDEMIOLOGIC STRUCTURES

Different specific registries were developed by the regulatory agencies in the world.

The French register for breast implants was finally approved by the French Commission Nationale de l'Informatique et des Libertés (CNIL). Its effective establishment is imminent, as soon as the question of funding is resolved. (https://www.youtube.com/watch?v=wpdkXMEj60U) Moreover, France has established since 2010 a national network of 33 expert hematopathology reference centers, called LYMPHOPATH network. This government-supported structure is composed of multidisciplinary teams which perform a second diagnostic evaluation of all suspected cases in France (and also in Belgium) and provides a help to the clinician in order to develop an individualized treatment plan for the patient.
On an international scale, after the PIP crisis in 2010, an International Collaboration of Breast Registry Activities (ICOBRA) between Australia, Austria, Canada, France, Germany, Ireland, Italy, the Netherlands, New Zealand, South Africa, UK and the USA was developed to harmonize the breast implant registries worldwide and to allow a more efficient potential future recall of breast implant. (71)

Likewise, in the Netherlands, the Dutch Breast Implant-Associated ALCL Consortium, consisting of a multidisciplinary group of scientists, investigates BIA-ALCL occurrence in women with breast implants.

(https://static1.squarespace.com/static/56fab39ad51cd464876ccecd/t/5a3c3fc39140b7cd5730b291/1513897924057/alcl-facts-figures-and-practical-guidelines.pdf)

A breast implant registry was also implemented in Australia (Australian Breast Device Registry) in 2012. (https://www.abdr.org.au/abdr-releases-2017-report-today/) Deva et al. (2019) insisted on the high penetrance of this registry. (15)

In the USA, the PROFILE (Patient Registry and Outcomes for Breast Implants and ALCL Etiology and Epidemiology), which is a joint collaboration between the ASPS, the Plastic Surgery Foundation and the FDA, was launched in August 2012. Thus, PROFILE was designed to record and centralize all past and future pathologically confirmed BIA-ALCL cases in the USA. PROFILE is an upgrade of the existing US medical device adverse reporting program MedWatch and the corresponding publicly available Manufacturer and User Facility Device Experience (MAUDE) database. However, this surveillance system was impaired by potential incomplete, inaccurate and/or unverified data. (46) Moreover, it was not designed to capture a body of data pertaining to BIA-ALCL pathogenesis and oncologic outcomes. (28)

A European Task Force was established in 2015 by an Expert Group of the European Union Commission to examine the possible correlation between BIA-ALCL and breast implants. A European database has been therefore formed that uniformly collects all reported BIA-ALCL cases by member countries. The database is managed and updated by each national Competent Authority.

The Table 2 summarizes the most updated data provided by the newly established registries and regulatory agencies in the French- or English-speaking countries in the
world. The data were retrieved from the respective regulatory agency websites.

Regarding the PROFILE registry, McCarthy et al. study was included because they
provided more complete outcomes than the respective website. (28)
<table><thead><tr><td>Country / countries</td><td>Name of the regulatory agency/registry</td><td>Date</td><td>Number of reports/unique cases</td><td>Number of related death</td><td>Number of pathologically confirmed cases</td><td>Number of textured implant involved</td><td>Number of smooth implants involved</td><td>Number of PU-coated implants involved</td><td>Risk</td></tr></thead><tbody><tr><td>USA</td><td>FDA</td><td>Sept 30, 2018</td><td>660 reports/457 unique cases</td><td>9</td><td></td><td>310</td><td>24</td><td></td><td>The FDA reported a risk between one in 3 817 and one in 30 000 women with textured implants based on the study</td></tr></tbody></table>
<table><tr><td>PROFILE</td><td>March 2018 (McCart hy 2019)</td><td>186 distinct cases</td><td>3 (one died of disseminated BIA-ALCL, one died of metastatic breast carcinoma and one died of natural causes)</td><td>70</td><td>4 (all patients had a history of prior textured permanent implant)</td><td>2</td><td>led by Loch-Wilkinson (2017) and Clemens (2017).</td></tr></table>
<table><tr><td></td><td></td><td>Feb 8, 2019</td><td>265 suspected/confirmed cases</td><td>0</td><td>16</td><td></td><td></td><td></td></tr><tr><td>Belgium</td><td>Federal Agency for Medicines and Health Products (FAMHP)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Canada</td><td>Health Canada</td><td>Jan 1, 2019</td><td></td><td>22</td><td>20</td><td>0</td><td></td><td></td></tr><tr><td>UK</td><td>Medicines and health care products regulatory authority (MHRA)</td><td>Sept, 2018</td><td>57 reports and 45 of which meet the WHO diagnostic criteria for BIA-ALCL</td><td>3 (only one of these is confirmed to meet the diagnostic criteria for BIA-ALCL)</td><td></td><td></td><td></td><td>1 per 24 000 implants sold</td></tr></table>
<table><tr><td>France</td><td>ANSM</td><td>between 2011 and November 2018</td><td>53</td><td>5 (two consequently to a breast cancer, one due to a heart attack and two related to BIA-ALCL)</td><td>50*</td><td>39 (among implants on diagnoses) and 57 (among all prior implants)</td><td>0</td><td>0 (among implants on diagnoses) and 1 (among all prior implants)</td><td></td></tr><tr><td>Australi<br/>a</td><td>Therapeutic Goods Administration (TGA)</td><td>11 January 2019</td><td>76 cases reported</td><td></td><td></td><td></td><td></td><td></td><td>estimated one in 1 000 to 10 000 chance of having this diagnosis</td></tr></table>
<table><caption>Table 2: Clinical data related to BIA-ALCL published by the newly established registries and regulatory agencies in the French- or English-speaking countries in the world</caption><tr><td>Ireland</td><td>Health Products Regulation Association (HPRA)</td><td>The HPRA has not received any reports of BIA-ALCL through its medical device vigilance reporting system.</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>EU</td><td>Task Force</td><td>November 2018</td><td>214</td><td></td><td>166</td><td>0</td><td></td></tr></table>

*After exclusion of some patients, 46 cases were finally confirmed by the LYMPHOPATH network in February 2019. 136 implants were identified.
The main limitation is that many registries depend on voluntary reports from participating physicians. However, some tendencies may be drawn from these early data. Thus, Scandinavian countries, with excellent implant registries, had almost no reported cases until recent. (72, 73) Likewise, a greater proportion of cases within the USA was reported at a more advanced stage of disease. (38)

Due to the delay to onset (approximately 10 years) and the late recognition as a specific entity, the reported BIA-ALCL cases still belong to the "take-off" phase and the exponential increase is not planned to stop. (69) It is reasonable to wait for the "plateau phase" in order to draw representative statistics. However, some health regulatory agencies recently released recommendations.

### 1.2.7. FIRST RECOMMENDATIONS FROM NATIONAL REGULATORY AGENCIES

The first major recommendation was issued by the French regulatory agency (ANSM), which held in February 2019 a public consultation on textured breast implants. Different stakeholders (other regulatory agencies, breast implant manufacturers, patients, surgeons and plastic surgeon societies) were interviewed by an expert committee. At the end of the consultation, the experts had to stand up on the following points:

* Are there situations for which the use of textured implants is compulsory in cosmetic surgery? What are they?

* Are there situations for which the use of textured implants is compulsory in reconstruction surgery? What are they?

The conclusions of the committee were published by press release:

* The committee recommended smooth implants

* The macrotexture Biocell from Allergan was banned

* Other "macrotextured" implants (ie from other brands) as well as PU-coated implants had to be very carefully used

* But no need to proceed to preventive explantation of macrotextured implants at that stage
* Textured implants may be advantageous in specific cases, in aesthetics as well as in reconstruction

* The committee emphasized the need to a uniformed classification of textures at European level

The use of smooth implants had been already recommended by the French plastic surgery societies in November 2018. These recommendations were also shared by some European countries (such as Belgium, Denmark and Iceland), although the position of the European Task Force continued to state "there is currently not enough scientific evidence of a causal relationship specifically between textured implants and BIA-ALCL". The European opinion was shared by the Italian Ministry of Health, which argued that "there is not statistical evidence to prove that smooth implants are not involved".

As of April, 4th 2019 the "macrotextured" implants (i.e. Biocell-textured implants, Sebbin shaped textured implants, Arion shaped textured implants, Nagotex-textured implants and POLYtxt-textured implants) were banned in France based in part on our results presented in chapter III). (https://www.youtube.com/watch?v=wpdkXMEj60U)
The "macrotextured" implants were then banned in Egypt and Tunisia.

Both saline and silicone-filled implants have been reported in association with BIA-ALCL without a statistical difference in frequency. (44) Therefore, it seems more likely that the silicone shell surface rather than the implant contents is involved in pathogenesis. (43) Moreover, the first case of BIA-ALCL was reported 10 years after the development of textured silicone surface implants, which approximately coincides with the median interval from implantation to diagnosis. (64) Therefore, breast implant surface, especially textured breast implant surface, is of prime importance in the pathogenesis of BIA-ALCL.
## 1.3.1. BREAST IMPLANT MANUFACTURING AND TEXTURE

A silicone gel-filled breast implant is composed of a thin silicone shell, inside which a silicone gel was inserted. Today, only one supplier (Nusil technology) provides all the implant manufacturers with a medical grade liquid silicone, mainly composed of straight chains of PolyDiMethylSiloxane (PDMS). (74) A silicone gel is a network of PDMS reticulated chains swollen with silicone fluid. The degree of reticulation (or cross-linking) and the average chain length (number of repeating monomers) determine the viscosity of the silicone gel and therefore the cohesiveness of the implant. (75) The implant shell is made of much more reticulated silicone elastomer. (76) The reticulation is controlled by the adding of cross-linkers and by heating, especially for the High Temperature Vulcanization (HTV) PDMS.

Basically, two parts (the “cross-linker” and the “base”) are provided. The “base” contains 99% of methyl vinylpolysiloxane and the catalyst (platinum complex) in infinitesimal quantities. The “cross-linker” also contains a high percentage of methyl vinylpolysiloxane and the cross-linker (methylhydrogen polysiloxane) Silica is added to increase the viscosity and the tensile strength. The manufacturers mix them according to specific proportions. An organic solvent (xylene or ethyl benzene) is added so that the solution is enough viscous to be moulded. (74)

All the process takes place in clean room (class 1000 for the dipping room and class 10 000 for the other rooms). (77)

Many companies do not have semi-automated processes and still manually dip reusable implant-shaped mandrels into liquid silicone for several seconds to produce a layer. Implant mandrels are made of lightweight polymer (such as Ertacetal®) or stainless steel, and are designed according to the final dimension of the implant. They also have a stem to be handled. The silicone-coated mandrel is then placed under laminar flow in order to completely evaporate the solvent. The mandrel is turned up down several times to equalize the thickness of the layer. This process is then repeated to form different layers superimposed. The number of layers depends on the
manufacturer and on the type of texture. Depending on the manufacturer, breast
implant shells have a thickness between 0.075 and 0.75 mm. (7)

For silicone gel-filled implants, one or several layers of another type of silicone, which have phenyl or trifluoropropyl-group in place of the methyl group, is sandwiched between PDMS layers. (76) These layers (called “low bleed barrier”) will prevent bleeding of the short chains contained in the silicone gel through the shell. The shell is therefore a trilaminar structure. The position of the barrier within the shell is manufacturer-dependent.

Once all the layers were moulded, the mandrels are placed into an oven to cure the
silicone. Interim curing may occur during the process. The shells are then peeled off
from the mandrel. The shell surface and thickness are thoroughly controlled in order to
have no defect. Destructive standardized mechanical tests are also performed. (78)

The opening created by the location of the stem is sealed by a silicone patch.
Information for the implant traceability (such as manufacturer name, implant
reference, serial number, volume ...) are present on the patch.

The liquid silicone gel is injected through the silicone patch with a syringe. The volume injected is computed according to the volume of the implant. A final curing allows to slightly reticulate the gel and to give the desired firmness of the implant.
The implant is finally placed into a blister and will be sterilized. (77)

The process described above is corresponding to a smooth implant. However,
different surface processing (or texture) were designed to create different states of
surface.

The most reported texturing processes are:

* "salt-loss technique." An additional step is introduced into the process: before curing, the silicone-coated mandrel is pushed into calibrated granular salt crystals (or other crystals). (Fig. 3) Once the surface has cured, this salt is then
dissolved in a water bath. (79) For some publications, a last silicone layer is
moulded to cover the salt crystals pitted in the silicone and after the curing,
the shell must be brushed in the bath to open the cavities. (80, 81)

<figure><img src="image_5.png" /><figcaption>Figure 3 : « Salt-loss technique » (77)</figcaption></figure>

* A PU foam was firstly bonded on the silicone surface (the method of fixation was not specified). The PU coating has been then vulcanized on the cured silicone shell since 1989. A second PU sheeting is used to cover the base of the implant. (18)

* A pressure imprint-stamping technique: the uncured silicone coated-implant is pushed into PU foam and then removed. The silicone surface will replicate the foam structure. (7)

* Sientra uses a proprietary texturing technology. According to some authors, the process is based on "gas expansion" (82), whereas others report a "volitization of ammonium carbonate" (83).

* Other processes use rough mandrel. Thus, the moulded silicone layers replicate the state of surface present on the mandrel. Once peeled off, the shell must be turned inside out so that the textured surface is on the outer surface of the implant. (80)

On the basis of the literature, the Table 3 reports for the different major manufacturers
the process of texturing used. All the types of texture do not have a commercial
trademark. Thus, for the textures manufactured by Sebbin and Arion, the shape of the
implant (round or anatomical) must be specified to distinguish the different textures. Interestingly, sometimes the commercial name of the texture given by some manufacturers reflects the tactile sensing that the surgeon is susceptible to have by touching the implant, such as Silk Surface™ or Velvet Surface™.

<table><thead><tr><td>Manufacturer</td><td>Commercial name of the implant surface*</td><td>Surface texturing process</td><td>CE marked/FDA approved</td></tr></thead><tbody><tr><td>Cox Uphoff International (CUI)/Allergan, Irvine, CA, USA</td><td>Microcell</td><td>Salt loss (79)</td><td>YES/NO</td></tr><tr><td>Allergan</td><td>Biocell</td><td>Salt loss (84)</td><td>YES/YES</td></tr><tr><td>Mentor, Irvine, CA, USA</td><td>Siltex</td><td>"Negative contact imprinting with polyurethane foam" (83)</td><td>YES/YES</td></tr><tr><td>Silimed, Rio de Janeiro, Brazil</td><td>TRUE Texture</td><td>"Volitization of ammonium carbonate with heat" (83)</td><td>NO/YES</td></tr><tr><td>Silimed</td><td>Pure Polyurethane</td><td>« Polyurethane bonded foam » (85)</td><td>NO/NO</td></tr><tr><td>Sebbin, Boissy l'Aillerie, France</td><td>NanoSkin or Sebbin round microtextured implant</td><td>"Moulding silicone layers on a sandblasted mandrel" (80)</td><td>YES/NO</td></tr><tr><td>Sebbin</td><td>Round textured implant</td><td>Salt loss (80)</td><td>YES/NO</td></tr><tr><td>Sebbin</td><td>Shaped textured implant</td><td>Salt loss (80)</td><td>YES/NO</td></tr><tr><td>Cereplas</td><td>Cereform</td><td>"chuck moulded manufactured implant" (86)</td><td>Production stopped</td></tr></tbody></table>
<table><caption>Table 3: Textures of the major breast implant manufacturers and associated texturing processes</caption><tr><td>PIP</td><td>VELVET</td><td>Salt loss (86)</td><td>Production stopped</td></tr><tr><td>Perouse-Plastie</td><td>Perthese</td><td>“Produced directly by the mandril” (87)</td><td>Production stopped</td></tr><tr><td>Eurosilicone, GC<br>Aesthetics,<br>Dublin, Ireland</td><td>CRISTALLINE<br>Microtextured</td><td>Salt loss (86)</td><td>YES/NO</td></tr><tr><td>Eurosilicone</td><td>CRISTALLINE<br>Textured</td><td>Salt loss (85)</td><td>YES/NO</td></tr><tr><td>Nagor, GC<br>Aesthetics,<br>Dublin, Ireland</td><td>Nagotex</td><td>Salt loss (84)</td><td>YES/NO</td></tr><tr><td>Polytech,<br>Dieberg,<br>Germany</td><td>MESMO</td><td>Unknown</td><td>YES/NO</td></tr><tr><td>Polytech</td><td>POLYtxt</td><td>«Vulcanisation (ammonium carbonate)» (85)</td><td>YES/NO</td></tr><tr><td>Arion, Mougins,<br>France</td><td>Round and<br>shaped micro-<br>textured<br>implant</td><td>Unknown</td><td>YES/NO</td></tr><tr><td>Arion</td><td>Round and<br>shaped<br>textured<br>implant</td><td>[Sugar pitting] (88)</td><td>YES/NO</td></tr><tr><td>Establishment<br>Labs SA, Coyol<br>de Alajuela,<br>Costa Rica</td><td>Silk Surface</td><td>“chuck moulded<br>manufactured implant”<br>(86)</td><td>YES/NO</td></tr><tr><td>Establishment<br>Labs SA</td><td>Velvet Surface</td><td>“chuck moulded<br>manufactured implant”<br>(86)</td><td>YES/NO</td></tr></table>
*Where no commercial name exists, the shape of implant and the type of surface are given.

The silicone gel can be replaced by other types of filling (such as saline solution or hydrogel). However, the shell structure must be modified. For example, for inflatable saline-filled implants, the manufacturers use another type of silicone: the Room Temperature Vulcanized (RTV) silicone, in order not to form ripples on the shell surface. (77) Soya oil-filled implants were attempted with Trilucent breast implants from LipoMatrix in 1995. However, they were removed from the market in 2000 due to suspicion of carcinogenicity. PIP developed implants filled with hydrogel in the 1990s and were voluntary withdrawn from the market in December 2000. (15)

Manufacturing process of breast implant, especially the mechanical strength of the shell, is validated by international standards. The next paragraph reviews international and national standards relative to breast implant surface.

### 1.3.2. THE STANDARDS RELATED TO BREAST IMPLANT SURFACE MEASUREMENT

The only requirement relative to breast implant surface specified in the American Society for Testing and Materials (ASTM) standards is that surface texture "may not alter the other characteristics of the device" (ASTM F2051 – 00(20067), ASTM F703 – 07). Although informative, the Appendix H of the ISO (International Organization for Standardization) 14607:2018 standard is slightly more detailed on the methodology to measure the breast implant surface. Basically, the sampling and the instruments are specified. For the surface measurements, 3 representative shells must be used. On each shell, 15 measures of 4mm² must be performed. The instrument must be chosen among:

* the SEM with a 2D and 3D surface reconstruction software.

* White-Light Interferometry

* Laser Confocal Microscopy

* High Range Atomic Force Microscopy (AFM)

The following parameters should be reported:
* Pore size or pore diameter (µm),

* Number and height (µm) of peaks and resulting kurtosis,

* Number and depth (µm) of valleys and resulting skewness,

* Average distance between morphological features (µm), i.e. morphological density,

* Mean peak height (µm),

* Arithmetic roughness (Ra or Sa) and Root mean square roughness (Rms),

* Maximum peak height (Rz or Sz).

Only the kurtosis (Sku), the skewness (Ssk), the arithmetic roughness (Sa), the Root mean square roughness (Rms) and the maximum peak height (Sz) are metrologically standardized. (ISO 13565)

The ISO 14607:2018 standard replaces the ISO 14607:2009 standard, in which only measurements by SEM were allowed. The standard also specified that 9 measurements of 4mm² had to be performed and that the average characteristics of the surface (i.e. dimensions of the pores, peaks or hollows) had to be recorded.

More and more studies measuring breast implant surface were led. The next paragraph analyses their compliancy with the ISO-required measurement methodology.

### 1.3.3. BREAST IMPLANT SURFACE MEASUREMENTS PUBLISHED IN THE LITERATURE

The SEM were extensively used in the literature to image the surface of breast implant. In 2001, Danino published the first SEM images of the two most sold textures in the world: the Biocell texture and the Siltex texture. (89) However, topographical analysis of breast implant surface really began from 2014.

The first use of Laser Confocal Microscope was documented by Valencia-Lazcano et al. in 2014, who provided the first 3D images of breast implant surfaces. (90) It is only very recently that surfaces exhibiting more complex structures, such as a PU foam, were measured by Laser Confocal Microscope. (84) This instrument was then used by
Barr et al. (86) to measure a comprehensive range of breast implant surface and then by James et al. (91)

3D surface images of a textured and a smooth breast implant respectively obtained by 3D laser scanner and AFM were reported by Kyle et al. in 2015. (92) Barr et al. also specified that the smooth implant in their series was measured by AFM. (93)

The first use of Micro-tomography was published by Atlan et al. in 2015. (79) However, only cross-sections of the surface were provided. In 2018, Atlan et al. performed the same analysis on a larger range of breast implant, without more details. (94) In the same year, Jones et al. described a methodology to extract 3D surface images and roughness parameters from a micro-tomographic measurement, which consisted of "wrapping the sample to avoid overhangs and cavities". (85) Jones et al. also concluded that the Micro-tomography provides "a more accurate morphologic assessment of the entire implant shell".

The first study in compliance with the ISO 14607:2018 was documented by a report mandated by the French health authority (ANSM) and published online in July 2018. Basically, the authors performed measurements of a large range of breast implants with a SEM equipped with a four quadrants backscattered electron (BSE) detector, which allowed them to provide 4 images of the same surface under 4 different angles. The software of topographical analysis Mountains was then used to obtain a 3D image of the surface from the 4 images. This 3D reconstruction relies on the principle of the stereoscopy, which consists in creating an illusion of relief by superimposing two captures of the same image shot under two slightly different angles. The authors also specified that for smooth or slightly rough surfaces, a higher magnification has been used to capture the state of surface. Thus, for these surfaces, the measurements were performed on an area lower than 4mm².

The Table 4 summarizes the values reported in the literature of the most mentioned metrological parameter specified in the ISO 14607:2018 standards (i.e. Sa). To facilitate the comparison between the different studies, the surface sampling is restricted to the
two most quoted textured surfaces (Biocell and Siltex) and the two most quoted smooth surfaces (Allergan smooth implant and Mentor smooth implant).

<table><caption>Table 4: Topographical measurements and characterizations published in the literature</caption><thead><tr><th></th><th></th><th>Kyle et al. (92)</th><th>Valencia et al. (95)</th><th>Barr et al. (86)</th><th>Jones et al. (85)</th><th>James et al. (91)</th></tr></thead><tbody><tr><td>Sampling</td><td></td><td>6 repetitions</td><td>5 repetitions</td><td>5 repetitions</td><td>NP</td><td>6 repetitions</td></tr><tr><td>Surface area</td><td></td><td>1x1cm² (Siltex) 90x90µm² (smooth)</td><td>644x642µm</td><td>NP</td><td>NP</td><td>4.8mm² ± 0.2mm²</td></tr><tr><td>Compliance with the ISO 14607:2018 or ISO 14607:2009 standard?</td><td></td><td>NO</td><td>NO</td><td>NO</td><td>NO</td><td>NO</td></tr><tr><td rowspan="4">Sa values</td><td>Biocell</td><td>NP</td><td>18.83µm</td><td>80.03µm</td><td>91.7µm</td><td></td></tr><tr><td>Siltex</td><td>8240nm</td><td>8.88µm</td><td>43.07µm</td><td>51.4µm</td><td></td></tr><tr><td>Allergan smooth implant</td><td>NP</td><td>0.07µm</td><td>NP</td><td>8.5µm</td><td></td></tr><tr><td>Mentor smooth implant</td><td>22.2nm</td><td>0.06µm</td><td>1.07µm</td><td>2.1µm</td><td></td></tr></tbody></table>

NP : Not Provided

The Sa values obtained on Biocell-textured and Siltex-textured surfaces exhibit large discrepancies between the studies of Kyle et al. (92) and Valencia et al. (95) and the ones of Barr et al. (86) and Jones et al. (85), although Valencia et al. (95) and Barr et al. (86) used the same measuring instrument. This inconsistency is also observed on smooth surfaces measured by AFM. (86, 92) The micro-tomograph with a voxel size of
15µm measured a 4 times higher Sa on Allergan smooth implant than Mentor smooth implant. (85)

In conclusion, the measurement methodologies published in the literature are not
compliant with the ISO standards. We will now study if, although elusive (especially in
the ISO 14607:2009), the surface indicators suggested by the standards are used in the
literature.

1.3.4. BREAST IMPLANT SURFACE DESCRIPTION

The terms used to morphologically describe the textures in the literature were
numerous and not accurate (Table 5). Authors have attempted to describe breast
implant surfaces using variable terms: some referred to "peaks and valleys", some to
"nodules", and others to "concavities" or "indentations". Similarly, authors reported
that some surfaces are more "aggressive" than others.
<table><thead><tr><th></th><th>Siltex</th><th>Biocell</th><th>Micro cell</th><th>PU-coated implant*</th><th>TRUE Texture</th><th>Sebbin anatomical implant</th><th>CRISTALLINE Microtextured</th><th>CRISTAL LINE Texture d</th><th>Nago tex</th><th>POLY txt</th><th>Smooth implant*</th></tr></thead><tbody><tr><td>Nodule</td><td>(79, 86, 89, 90, 95-97)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Concavities</td><td></td><td>(98)</td><td></td><td>(98)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Indentation</td><td></td><td>(7, 86, 97, 99)</td><td></td><td></td><td></td><td>(86)</td><td>(86)</td><td></td><td></td><td></td><td></td></tr><tr><td>Depression</td><td></td><td>(86, 89, 96)</td><td></td><td></td><td></td><td>(86)</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Undulation</td><td>(98)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Open-pore</td><td></td><td>(79, 89, 94, 96, 98, 99)</td><td>(94)</td><td>(98)</td><td></td><td></td><td></td><td>(94)</td><td>(94)</td><td></td><td></td></tr><tr><td>Fully enclosed pores</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>(94)</td><td></td></tr><tr><td>Porosity</td><td></td><td></td><td></td><td>(98)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Wells</td><td></td><td>(79, 90, 95, 97)</td><td></td><td></td><td></td><td>(79)</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Pits</td><td></td><td>(95, 97)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>(90, 95)</td></tr><tr><td>Spiderweb</td><td></td><td></td><td></td><td>(97)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Mesh network</td><td></td><td></td><td></td><td>(97)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>
<table><tr><td>Peaks</td><td>(79, 90, 95, 97)</td><td>(95)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Crevasses</td><td>(90, 95, 97)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Polyhedra</td><td></td><td>(95)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Aggressive</td><td></td><td>(89, 96)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Islands</td><td>(86)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Troughs</td><td>(86)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Surface irregularity</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>(86)</td></tr><tr><td>Nano-scale roughness</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>(86)</td></tr><tr><td>Hollow pore</td><td></td><td></td><td></td><td>(86)</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Fenestration</td><td></td><td></td><td></td><td>(86)</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Open cell</td><td></td><td></td><td>(86)</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Ridges</td><td>(97)</td><td>(95, 97)</td><td></td><td></td><td></td><td></td><td></td><td></td><td>(7, 95)</td></tr><tr><td>Rocky</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>(90, 95)</td></tr><tr><td>Ripples</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>(97)</td></tr></table>
<table><caption>Table 5: Morphological descriptions of the textures in the literature</caption><tr><td>Fibrils</td><td></td><td></td><td>(97)</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Valleys</td><td>(79, 95)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Open dome</td><td></td><td></td><td></td><td></td><td>(79)</td><td></td><td></td><td></td><td></td></tr><tr><td>Lattice structure</td><td></td><td></td><td>(99)</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Projections</td><td></td><td>(99)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Caves</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>(85)</td></tr><tr><td>Interconnected skeletal framework</td><td></td><td></td><td>(79)</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Irregular sponge-like surface</td><td></td><td></td><td>(94)</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Overhangs/lip</td><td></td><td>(94)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></table>
* As we suppose non-significant differences between the different smooth implants and between the different PU-coated implants sold by the different manufacturers, the latter are not mentioned for these cases. (91)

The descriptive terms are not only multiple and inaccurate: they are also inconsistent. A same term may designate very different textures. Thus, "concavities" or "open pore" characterize both salt-loss obtained texture and PU coating. Likewise, "pits" were used to describe Biocell textured and smooth implants.

As early as first textured implants were commercialized, categories of texture were emerged from the portfolio of manufacturers, such "macrotexture", "microtexture" or even "nanotexture". By associating an intended clinical outcome and/or presumed innovating process (at least presumed different from the others), these terms rapidly became the corner stone of the marketing concept developed by the manufacturers. Thus, according to a manufacturer-sponsored study, "the Motiva Implants are a novel breast implant technology" and their nanotexture was "designed to reduce the abrasion when the implant is in contact with the tissue". (100) Another manufacturer-sponsored study (94) claimed a "greater tissue adherence with the Biocell texture" through the "Velcro effect" (89). Consequently to the commercial success of the Biocell-textured implants sold by Allergan, the surgeons associated a sensory perception to the term "macrotexture". Thus, the "feel to the touch" of a macrotextured implant was similar as the one of a peach or a velvet fabric (hence, the "peach skin effect" or "velvet effect"). Likewise, an implant could be qualified as "macrotextured", when the surface structures are visible to the naked eye. (101) Furthermore, when an implant was not sold as "macrotextured" or "nanotextured", the implants were either "textured" or "microtextured". Most of the time, the choice between these two terms did not rely on marketing arguments or subjective assessments any more, but often depended on the number of textures sold by the manufacturers and on the current trends. As a result, this multiplicity of trade names and jargons and the paucity of unique nomenclature preclude any relevant inter-brand comparison. (102)
As highlighted by the ANSM-mandated committee, establishment of an uniformized
classification is of the utmost importance.
(https://www.youtube.com/watch?v=wpdkXMEj60U)

## 1.4. NOMENCLATURE AND CLASSIFICATION OF BREAST IMPLANT SURFACE

To attempt to rationalize the different denominations, five nomenclatures based on
surface parameters emerged. The first four ones proposed a quantifiable surface
parameter, on which the nomenclature was based, as well as the boundaries of each
category. (78, 85, 86, 94). The fifth nomenclature described in the ANSM-mandated
report demonstrated for the first time by a robust statistical analysis the retained
surface parameters. (https://ansm.sante.fr/S-informer/Points-d-information-Points-d-
information/Surveillance-des-implants-mammaires-par-l-ANSM-publication-d-un-avis
d-experts-de-CSST-et-d-une-etude-sur-la-texturation-Point-d-information) Of the first
four nomenclatures, one was drawn from the ISO 14607:2018 standard. (78) The other
three nomenclatures provided different biological evidence to support the
nomenclature, which will be discussed in the section "biological models".

Barr et al. and the ANSM-mandated experts performed measurements on one of the
specified instruments in the ISO 14607:2018 standard (i.e. the Laser Confocal
Microscopy and the SEM with a 3D reconstruction software). (86) The two others used
Micro-tomography with a voxel size of 15µm and 2.2µm for all the breast implant
surfaces (including the smooth implants). (85, 94)

Barr et al. published in 2017 the first nomenclature established on a metrologically
standardized parameter (i.e. Sa). (86) They also added a second level based on the
presence or absence of porosity assessed from SEM images. Likewise, the ISO
14607:2018 standard proposed on the basis of the Sa 3 categories to describe the
breast implant surfaces: "smooth", "microtexture" and "macrotexture". Thus, a
"macrotexture" has a Sa either superior to 75µm (86) or superior to 50µm. (78)
Therefore, the Sa range defining a "microtexture" is comprised between 10 and 75µm
or between 10 and 50µm, according to Barr et al. and to the ISO 14607:2018
respectively. The major discrepancy remains on the other categories: Barr et al. added a mesotexture category (Sa<15µm) and a nanotexture category (Sa<5µm), whereas smooth implant is the third category of the ISO standard (Sa<10µm).

Atlan et al. reported a nomenclature according to a custom-made parameter (called "surface area") expressed as an absolute value. (94) This article mentioned for the first time that a nomenclature must be morphologically relevant first and foremost in regard to some specific surface structures, such as pore size, pore number, texture depth or complexity.

The first nomenclature, which did not use the terms of "macrotexture" or "microtexture" was established by Jones et al. (85) They preferred the terms of « *high* », « *intermediate* », « *low* » and « *minimal* » surface area. The surface area was here normalized in comparison to a smooth implant. They demonstrated a correlation between surface area and Sa and insisted that the nomenclature was uncorrelated with the texturing processes. According to Rastogi et al., "this proposed grading system objectively categorizes implant texture morphology and is arguably superior to existing descriptive terms". (70)

The ANSM-mandated nomenclature was obtained by Principal Component Analysis (PCA). This statistical analysis was designed to reduce the initial number of parameters to only two variables called Principal Components (PC), which are a linear combination of the initial parameters. The PC are mathematically built in order to maximize the variance. By only retaining the first two terms of each PC, the authors were able to constitute 4 groups: the "smooth", the "microtexture", the "macrotexture" and the "polyurethane". A linear equation of the frontiers was then found. Moreover, on the basis of SEM images, they qualitatively identified different surface structures among the "macrostructures": the "cubic structure", the "rumpled surface", the "globular surface" and the "surfaces with indeterminate imprint".

The Table 6 precise the category of each breast implant surface according to the mentioned nomenclatures. The ISO 14607:2018 did not detail the ranking of the different breast implant surfaces into the proposed groups.
<table><thead><tr><th></th><th>Barr et al. (86)</th><th>Atlan et al. (94)</th><th>Jones et al. (85)</th><th>ANSM report</th></tr></thead><tbody><tr><td>Smooth implants*</td><td>Nanotexture</td><td>Smooth/nanotexture</td><td>Minimal</td><td>Smooth</td></tr><tr><td>SilkSurface</td><td>Mesotexture</td><td>Smooth/nanotexture</td><td>Minimal</td><td>Microtexture</td></tr><tr><td>VelvetSurface</td><td>Microtexture non-porous</td><td>Smooth/nanotexture</td><td>Minimal</td><td>Microtexture</td></tr><tr><td>Arion Microtextured</td><td>NM</td><td>NM</td><td>NM</td><td>Microtexture</td></tr><tr><td>Sebbin Microtextured</td><td>NM</td><td>NM</td><td>NM</td><td>Microtexture</td></tr><tr><td>Cereform</td><td>Microtexture non-porous</td><td>NM</td><td>NM</td><td>NM</td></tr><tr><td>MESMO</td><td>NM</td><td>Microtexture</td><td>NM</td><td>Macrotexture</td></tr><tr><td>Microcell</td><td>NM</td><td>Microtexture</td><td>NM</td><td>Macrotexture</td></tr><tr><td>VELVET</td><td>Microtexture porous</td><td>NM</td><td>NM</td><td></td></tr><tr><td>Siltex</td><td>Microtexture non-porous</td><td>Microtexture</td><td>Low</td><td>Macrotexture</td></tr><tr><td>Sebbin round textured implant</td><td>NM</td><td>NM</td><td>NM</td><td>Macrotexture</td></tr><tr><td>CRISTALLINE Microtextured</td><td>Microtexture porous</td><td>NM</td><td>NM</td><td>Macrotexture</td></tr><tr><td>CRISTALLINE Textured</td><td>NM</td><td>Macrotexture</td><td>Intermediate</td><td>Macrotexture</td></tr><tr><td>POLYtxt</td><td>Microtexture non-porous</td><td>Macrotexture+</td><td>Intermediate</td><td>Macrotexture</td></tr><tr><td>TRUE Texture</td><td>Microtexture porous</td><td>Macrotexture</td><td>NM</td><td>Macrotexture</td></tr><tr><td>Nagotex</td><td>NM</td><td>Macrotexture+</td><td>Low</td><td>Macrotexture</td></tr></tbody></table>
<table><caption>Table 6: Classifications of the different breast implant surfaces according to the published nomenclatures</caption><tr><td>Sebbin shaped textured implant</td><td>Macrotexture porous</td><td>NM</td><td>NM</td><td>Macrotexture</td></tr><tr><td>Arion textured implant</td><td>NM</td><td>NM</td><td>NM</td><td>Macrotexture</td></tr><tr><td>Biocell</td><td>Macrotexture porous</td><td>Macrotexture</td><td>Intermediate</td><td>Macrotexture</td></tr><tr><td>PU-coated*</td><td>Not classed</td><td>Macrotexture+</td><td>High</td><td>PU</td></tr></table>

* As we suppose non-significant differences between the different smooth implants and between the different PU-coated implants sold by the different manufacturers, the latter are not mentioned for these cases. (91)

NM: Not Measured

Numerous inconsistencies between the 4 nomenclatures of the table are observed. For example, if we exclude Jones' article (which used a totally different nomenclature system), only the Biocell texture belongs to the same category (i.e. "macrotexture") in the 3 other articles.

Moreover, a prior knowledge is often necessary to identify some types of texture analyzed in the articles, especially for the manufacturers which commercialize several types of texture without commercial names. For example, the "SL2Sebbin" texture analyzed by Barr et al. was identified as the texture of Sebbin shaped implant by analogy between the SEM images provided by Barr et al. and in the FDA-mandated report.

Once topographically consistent categories of breast implant surface will have been established, we will be able to confront the nomenclatures to the safety data in order to demonstrate or refute our hypothesis stating that a relationship exists between some
morphological structures and some clinical complications. Thus, clinical evidence
categorized by implant groups must be compiled.

**1.5. CLINICAL EVALUATION OF BREAST IMPLANT SURFACE**

**1.5.1. OBJECTIVES AND GENERAL PRINCIPLES OF CLINICAL EVALUATION VIA LITERATURE REVIEW**

To study the clinical impact of some types of texture, a selective literature review was
led in order to retain only the articles which:

* clearly mention the name of the implant manufacturer and the commercial type of texture

* provide safety data on severe complications which are not due to the surgery or to implant characteristics other than the texture (i.e. gel, shell integrity ...). Thus, data on complications associated to the surgery, such as infection, hematoma, early seroma, abnormal scarring or ptosis, were not retained in the analysis. Likewise, complications, for which the texture has clearly no impact, such as implant rupture or implant wrinkling/rippling, were not also taken into account. The complications, for which the assessment is not based on quantifiable markers or on a scale and relies on subjective criteria (such as implant rotation or implant malposition) were also excluded. Therefore, only the capsular contracture, BIA-ALCL, late seroma and double capsule were encompassed in the literature review. A seroma is considered as late when it occurs after 1-year post-implantation. A double capsule is constituted of a thin inner membrane adherent to the implant surrounding by an outer and totally separated membrane. (103)

The most robust clinical evidence on a medical device is provided by clinical studies.
Thus, more and more regulatory agencies assess the safety of a device on the basis of
clinical studies. They are even mandatory for Class III devices. Clinical studies consist
to follow a cohort of patients recruited by one center (monocentric) or by several
centers (multicentric) over a given period (or maximal follow-up). At regular interval,
visits are scheduled between the patient and the surgeon. At each visit, any side
effects are reported. The surgeon is either free to organize the patient care (observational study) or is enforced by the study to follow a strict medical protocol (interventional study). Different designs of follow-up exist: the patients are followed from the inclusion visit to the last visit (prospective study) or the surgeon decides to include a series of patients at a given time point and all the patient history is retrieved from the patient files (retrospective study).

In our case, the most valuable studies are observational and prospective. A major drawback of these studies is that 100% of the patient are not followed until the end of the study: some patients may be “lost” because they moved to another city for example. To take into account this number of “lost” patients, the outcomes are usually given as a cumulative risk (in percentage) provided by the Kaplan-Meier statistics. The log-rank test is designed to compare two cumulative risks. (104)

In order not to be biased by some confounding variables, such as radiotherapy (usually underwent by patients after breast cancer) or anterior implant exchange (thus, the implantation of the new device is a revision surgery), the results are often presented into 4 different cohorts: the primary Augmentation cohort, the revision Augmentation cohort, the primary Reconstruction cohort and the revision Reconstruction cohort.

However, clinical studies are not designed to properly assess some rare complications, such as BIA-ALCL (see the very low incidence of the section “BIA-ALCL”). In this case, clinical evidence must be based on the report cases, which are at best compiled in published reviews or in national or international registries. Regarding double capsule, two rates were documented with Biocell-textured implants: two in 10 000 and approximately 1% in over 7 000 patients). However, an accurate estimation of incidence was plagued by clinical misreading. Late seroma incidence was assessed at one in 1 000. (103)

Capsular contracture is dependent on a myriad of different factors, including the texturing. Numerous systematic reviews and meta-analyses of randomized controlled trials demonstrated benefits to texturing in reducing rates of capsular contracture.
(105-107) However, prospective trials led on longer follow-up reported no significant
differences in capsular contracture risks between smooth and textured implants. (108)

**1.5.2. CLINICAL EVALUATION OF A LINK BETWEEN SOME TYPES OF TEXTURES AND THE INCIDENCE OF CAPSULAR CONTRACTURE**

As mentioned previously, to establish that the risk of capsular contracture is potentially
impacted by some types of texture, a selective literature review of clinical studies was
led.

1.5.2.1. METHODOLOGY OF THE CLINICAL EVALUATION VIA LITERATURE REVIEW

The details of the methodology are specified below.

* Date of the research

The research was performed on February, 7th 2019.

- Literature sources used to identify articles

Both Pubmed and Google Scholar were used to identify literature data. For all
searches performed in Google Scholar, patents and citations were excluded.

* Selection criteria used to choose articles*

The selection criteria were the following:

o article in English or in French

o article assessing silicone gel-filled implants and more particularly one
identified type of texture (commercial name of the texture and
manufacturer given). If several commercial types of texture are included
in the study, results must be presented by type of texture.

o multicentre clinical study

o article reporting the risk of capsular contracture per patient (computed
according to the Kaplan-Meier statistics) in the primary augmentation
cohort. Being graded in severity on a scale of I to IV according to the
Baker classification, only the Baker III or IV will be considered as a
complication. (109)
* follow-up greater or equal to 2 years for safety data

* full text available

* number of patients greater or equal to 500

* no Acellular Dermal Mesh (ADM) used

* Database search details

Different searches were implemented to encompass the different textures of breast implants on the market.

Two types of search were launched on PubMed:

* One for the texture with a commercial name (Siltex, SilkSurface, VelvetSurface, Biocell, Microcell, Perthese, Cereform, Nagotex, TRUE Texture, POLYtxt, MESMO)

* Another for the texture without commercial name (Sebbin, Eurosilicone, Arion)

As the search is restricted to silicone texturing, smooth and PU-coated breast implants were excluded. Likewise, the search did not encompass VELVET (PIP) because the clinical outcomes are thought to be skewed by the use of fraudulent silicone.

As Sebbin and Eurosilicone have two different textures for their round implant and for their shaped implant (https://www.sebbin.com/fr/page/5/; https://www.gcaesthetics.com/products/), two searches were implemented with Google Scholar by precising "round" and "anatomical". (Table 7)

The workflow of the search is schematically represented in the Figure 4.
<table><thead><tr><th>Scientific database</th><th>Document type</th><th>Search terms</th><th>N° of documents</th></tr></thead><tbody><tr><td rowspan="3">Medline (PubMed)</td><td rowspan="3">Scientific study</td><td>("breast implants"[MeSH Terms] OR ("breast"[All Fields] AND "implants"[All Fields]) OR "breast implants"[All Fields]) AND (("mentors"[MeSH Terms] OR "mentors"[All Fields] OR "mentor"[All Fields]) OR Siltex™[All Fields]) AND (multicenter[All Fields] OR multicentre[All Fields]) AND "humans"[MeSH Terms]</td><td>10</td></tr><tr><td>("breast implants"[MeSH Terms] OR ("breast"[All Fields] AND "implants"[All Fields]) OR "breast implants"[All Fields]) AND (Motiva[All Fields] OR (establishment[All Fields] AND labs[All Fields]) OR SilkSurface[All Fields] OR VelvetSurface[All Fields]) AND (multicenter[All Fields] OR multicentre[All Fields]) AND "humans"[MeSH Terms]</td><td>0</td></tr><tr><td>SEBBIN[All Fields] AND ("breast implants"[MeSH Terms] OR ("breast"[All Fields] AND "implants"[All Fields]) OR "breast implants"[All Fields])</td><td>4</td></tr><tr><td></td><td></td><td>("breast implants"[MeSH Terms] OR ("breast"[All Fields] AND "implants"[All Fields]) OR "breast implants"[All Fields]) AND</td><td>16</td></tr></tbody></table>
<table><tr><td>(Allergan[All Fields] OR Natrelle[All Fields] OR Inamed[All Fields] OR McGhan[All Fields] OR Biocell[All Fields]) AND (multicenter[All Fields] OR multicentre[All Fields]) AND "humans"[MeSH Terms]</td><td></td></tr><tr><td>("breast implants"[MeSH Terms] OR ("breast"[All Fields] AND "implants"[All Fields]) OR "breast implants"[All Fields]) AND (CUI[All Fields] OR Microcell [All Fields]) AND (multicenter[All Fields] OR multicentre[All Fields]) AND "humans"[MeSH Terms]</td><td>0</td></tr><tr><td>("breast implants"[MeSH Terms] OR ("breast"[All Fields] AND "implants"[All Fields]) OR "breast implants"[All Fields]) AND (Perouse[All Fields] OR Perthese [All Fields]) AND (multicenter[All Fields] OR multicentre[All Fields]) AND "humans"[MeSH Terms]</td><td>0</td></tr><tr><td>("breast implants"[MeSH Terms] OR ("breast"[All Fields] AND "implants"[All Fields]) OR "breast implants"[All Fields]) AND (Cereplas[All Fields] OR Cereform [All Fields]) AND (multicenter[All Fields] OR multicentre[All Fields]) AND "humans"[MeSH Terms]</td><td>0</td></tr></table>
<table><tr><td></td><td>("breast implants"[MeSH Terms] OR ("breast"[All Fields] AND "implants"[All Fields]) OR "breast implants"[All Fields]) AND (Nagor[All Fields] OR Nagotex[All Fields]) AND (multicenter[All Fields] OR multicentre[All Fields]) AND "humans"[MeSH Terms]</td><td>0</td></tr><tr><td></td><td>("breast implants"[MeSH Terms] OR ("breast"[All Fields] AND "implants"[All Fields]) OR "breast implants"[All Fields]) AND (Silimed[All Fields] OR Sientra [All Fields] OR True Texture[All Fields]) AND (multicenter[All Fields] OR multicentre[All Fields]) AND "humans"[MeSH Terms]</td><td>6</td></tr><tr><td></td><td>("breast implants"[MeSH Terms] OR ("breast"[All Fields] AND "implants"[All Fields]) OR "breast implants"[All Fields]) AND (Polytech[All Fields] OR POLYtxt[All Fields]) AND (multicenter[All Fields] OR multicentre[All Fields]) AND "humans"[MeSH Terms]</td><td>0</td></tr><tr><td></td><td>("breast implants"[MeSH Terms] OR ("breast"[All Fields] AND "implants"[All Fields]) OR "breast implants"[All Fields]) AND (Polytech[All Fields] OR MESMO[All Fields]) AND "humans"[MeSH Terms]</td><td>0</td></tr></table>
<table><tr><td></td><td></td><td>(multicenter[All Fields] OR multicentre[All Fields]) AND "humans"[MeSH Terms]</td><td></td></tr><tr><td></td><td></td><td>Eurosilicone[All Fields] AND ("breast implants"[MeSH Terms] OR ("breast"[All Fields] AND "implants"[All Fields]) OR "breast implants"[All Fields])</td><td>6</td></tr><tr><td></td><td></td><td>Arion[All Fields] AND ("breast implants"[MeSH Terms] OR ("breast"[All Fields] AND "implants"[All Fields]) OR "breast implants"[All Fields])</td><td>10</td></tr><tr><td></td><td></td><td></td><td></td></tr><tr><td rowspan="7">Google Scholar</td><td rowspan="7">Scientific study</td><td>allintitle: breast implants Mentor</td><td>12</td></tr><tr><td>allintitle: breast implants Motiva OR establishment OR labs</td><td>6</td></tr><tr><td>allintitle: SEBBIN round breast implants</td><td>0</td></tr><tr><td>allintitle: breast implants AND (Allergan OR Natrelle OR Inamed OR McGhan OR MacGhan)</td><td>13</td></tr><tr><td>allintitle: SEBBIN shaped breast implants</td><td>0</td></tr><tr><td>allintitle: SEBBIN anatomical breast implants</td><td>0</td></tr><tr><td>allintitle: breast implants AND (CUI OR Microcell)</td><td>0</td></tr><tr><td></td><td></td><td>allintitle: breast implants AND (Perouse OR Perthese)</td><td>0</td></tr></table>
<table><caption>Table 7: Search implemented on the scientific databases</caption><tr><td></td><td>allintitle: breast implants AND (Cereplas OR Cereform)</td><td>0</td></tr><tr><td></td><td>allintitle: breast implants AND (Nagor OR Nagotex)</td><td>0</td></tr><tr><td></td><td>allintitle: breast implants AND (Silimed OR Sientra OR True Texture)</td><td>0</td></tr><tr><td></td><td>allintitle: breast implants AND (Polytech OR POLYtxt)</td><td>0</td></tr><tr><td></td><td>allintitle: breast implants AND (Polytech OR MESMO)</td><td>0</td></tr><tr><td></td><td>allintitle: Eurosilicone round breast implants</td><td>0</td></tr><tr><td></td><td>allintitle: Eurosilicone shaped breast implants</td><td>0</td></tr><tr><td></td><td>allintitle: Eurosilicone anatomical breast implants</td><td>0</td></tr><tr><td></td><td>allintitle: breast implants Arion</td><td>1</td></tr></table>

84 articles were therefore identified.
<figure><img src="image_6.png" /><figcaption>Figure 4: Workflow for the selection of articles from the scientific databases</figcaption></figure>

1.5.2.2. LIST OF THE SELECTED AND NON-SELECTED ARTICLES IN THE LITERATURE REVIEW

After deleting the 15 duplicates, 69 articles were firstly retained. The list is detailed in
the Table 8, as well as the reasons for non-selection.
<table><thead><tr><td>N°</td><td>Study title</td><td>Author</td><td>Journal</td><td>Selected / Not Selected</td><td>Reason for non-selection</td></tr></thead><tbody><tr><td>1</td><td>The Mentor Study on Contour Profile Gel Silicone MemoryGel Breast Implants.</td><td>Cunningham B</td><td>Plast Reconstr Surg</td><td>Yes</td><td></td></tr><tr><td>2</td><td>Breast Implant-Associated Anaplastic Large Cell Lymphoma in Australia and New Zealand: High-Surface-Area Textured Implants Are Associated with Increased Risk.</td><td>Loch-Wilkinson A et al.</td><td>Plast Reconstr Surg</td><td>No</td><td>No data on capsular contracture</td></tr><tr><td>3</td><td>Indications for the use of MemoryShape breast implants in aesthetic and reconstructive breast surgery: long-term clinical outcomes of shaped versus round silicone breast implants.</td><td>Caplin DA</td><td>Plast Reconstr Surg</td><td>Yes</td><td></td></tr><tr><td>4</td><td>Breast implant rupture: causes, incidence, clinical impact, and management.</td><td>Handel N et al.</td><td>Plast Reconstr Surg</td><td>No</td><td>Not a clinical study</td></tr><tr><td>5</td><td>Mentor Contour Profile Gel implants: clinical outcomes at 6 years</td><td>Hammond DC et al.</td><td>Plast Reconstr Surg</td><td>No</td><td>Not a clinical study</td></tr><tr><td>6</td><td>Clinical experience with a fourth-generation textured silicone gel breast implant: a review of 1012 Mentor MemoryGel breast implants.</td><td>Stevens WG et al.</td><td>Aesthet Surg J</td><td>No</td><td>Monocentre retrospective study</td></tr><tr><td>7</td><td>Mentor Contour Profile Gel Implants: Clinical Outcomes at 10 Years.</td><td>Hammond DC et al.</td><td>Plast Reconstr Surg</td><td>Yes</td><td></td></tr></tbody></table>
<table><tr><td>8</td><td>The Mentor Core Study on Silicone MemoryGel Breast Implants</td><td>Cunningham B</td><td>Plast Reconstr Surg</td><td>No</td><td>70% of smooth implants were used</td></tr><tr><td>9</td><td>Preliminary (3 years) experience with smooth wall silicone gel implants for primary breast augmentation.</td><td>Seify H et al.</td><td>Ann Plast Surg</td><td>No</td><td>Retrospective study on less than 500 patients</td></tr><tr><td>10</td><td>Saline-filled breast implant safety and efficacy: a multicenter retrospective review</td><td>Cunningham B</td><td>Plast Reconstr Surg</td><td>No</td><td>Only saline-filled breast implants were used</td></tr><tr><td>11</td><td>Comments on "Preliminary 3-Year Evaluation of Experience With SilkSurface and VelvetSurface Motiva Silicone Breast Implants: A Single-Center Experience With 5813 Consecutive Breast Augmentation Cases"</td><td>Duscher D et al.</td><td>Aesthetic Surgery Journal</td><td>No</td><td>Not a clinical study</td></tr><tr><td>12</td><td>Preliminary 3-Year Evaluation of Experience With SilkSurface and VelvetSurface Motiva Silicone Breast Implants: A Single-Center Experience With 5813 Consecutive Breast Augmentation Cases</td><td>Sforza M et al.</td><td>Aesthetic Surgery Journal</td><td>No</td><td>Monocentre retrospective study</td></tr><tr><td>13</td><td>Discussion: Motiva Ergonomix Round SilkSurface Silicone Breast Implants Outcome Analysis of 100 Primary Breast Augmentations over 3 Years and Technical Considerations</td><td>Disa J</td><td>Plast Reconstr Surg</td><td>No</td><td>Not a clinical study</td></tr><tr><td>14</td><td>Reply: Motiva Ergonomix Round SilkSurface Silicone Breast Implants: The Tale of Goldilocks: Never Be</td><td>Huemer GM et al.</td><td>Plast Reconstr Surg</td><td>No</td><td>Not a clinical study</td></tr></table>
<table><tr><td></td><td>Afraid of Exploring Unknown Territory</td><td></td><td></td><td></td><td></td></tr><tr><td>15</td><td>Motiva Ergonomix Round Silksurface Silicone Breast Implants: Outcome Analysis of 100 Primary Breast Augmentations over 3 Years and Technical Considerations</td><td>Huemer GM et al.</td><td>Plast Reconstr Surg</td><td>No</td><td>Study on less than 500 patients</td></tr><tr><td>16</td><td>Response to "Comments on 'Preliminary 3-Year Evaluation of Experience With SilkSurface and VelvetSurface Motiva Silicone Breast Implants: A Single-Center Experience With 5813 Consecutive Breast Augmentation Cases'"</td><td>Sforza M</td><td>Aesthetic Surgery Journal</td><td>No</td><td>Not a clinical study</td></tr><tr><td>17</td><td>Comparison of Allergan, Mentor, and Sientra contoured cohesive gel breast implants: A single surgeon's 10-year experience</td><td>Doren EL et al.</td><td>Plast Reconstr Surg</td><td>No</td><td>Less than 500 patients</td></tr><tr><td>18</td><td>Experience with the Mentor Contour Profile Becker-35 expandable implants in reconstructive breast surgery</td><td>Hsieh F et al.</td><td>J Plast Reconstr Aesthet Surg</td><td>No</td><td>No silicone gel-filled implant was used</td></tr><tr><td>19</td><td>Shaped Silicone Gel Implants: Mentor MemoryShape Breast Implant</td><td>Rohrich RJ</td><td>Plast Reconstr Surg</td><td>No</td><td>Not a clinical study</td></tr><tr><td>20</td><td>Financial Disclosure Appendix for "Shaped Silicone Gel Implants: Mentor MemoryShape Breast Implant"</td><td>Calobrace MB et al.</td><td>Plast Reconstr Surg</td><td>No</td><td>Not a clinical study</td></tr><tr><td>21</td><td>Comparison of Allergan, Mentor, and Sientra Contoured Cohesive Gel Breast Implants: A Single Surgeon's 10-Year Experience</td><td>Sisti A et al.</td><td>Plast Reconstr Surg</td><td>No</td><td>Not a clinical study</td></tr></table>
<table><tr><td>22</td><td>Reply: Comparison of Allergan, Mentor, and Sientra Contoured Cohesive Gel Breast Implants: A Single Surgeon's 10-Year Experience</td><td>Afrooz PN et al.</td><td>Plast Reconstr Surg</td><td>No</td><td>Not a clinical study</td></tr><tr><td>23</td><td>Clinical Experience with Mentor Contour Profile MemoryGel Breast Implants: A Single Institution's Experience with 99 Consecutive Patients</td><td>Hirsch EM et al.</td><td>Plast Reconstr Surg</td><td>No</td><td>Less than 500 patients</td></tr><tr><td>24</td><td>Important Information for Reconstruction Patients About Mentor MemoryGel® Silicone Gel-Filled Breast Implants</td><td>Mentor corporation</td><td>N/A</td><td>No</td><td>Not a clinical study (patient brochure)</td></tr><tr><td>25</td><td>A 10-Year Prospective Study of Implant-Based Breast Augmentation and Reconstruction.</td><td>El-Haddad R et al.</td><td>ePlasty</td><td>No</td><td>Smooth implants were also used.</td></tr><tr><td>26</td><td>Characterization of Breast Implant Surfaces, Shapes, and Biomechanics: A Comparison of High Cohesive Anatomically Shaped Textured Silicone, Breast Implants from Three Different Manufacturers.</td><td>Atlan M. et al.</td><td>Aesthetic Plast Surg.</td><td>No</td><td>Not a clinical study</td></tr><tr><td>27</td><td>Descriptive analysis of the various mammary implants available on European market in 2005</td><td>Desouches C. et al.</td><td>Ann Chir Plast Esthet.</td><td>No</td><td>Not a clinical study</td></tr><tr><td>28</td><td>A scanning electron microscopy study of the surface of porous-textured breast implants and their capsules. Description of the</td><td>Danino A.</td><td>Ann Chir Plast Esthet.</td><td>No</td><td>Not a clinical study</td></tr></table>
<table><tr><td></td><td>"velcro" effect of porous-textured breast prostheses</td><td></td><td></td><td></td><td></td></tr><tr><td>29</td><td>Eight-year follow-up data from the U.S. clinical trial for Sientra's FDA-approved round and shaped implants with high-strength cohesive silicone gel.</td><td>Stevens WG et al.</td><td>Aesthetic Surgery Journal</td><td>Yes</td><td></td></tr><tr><td>30</td><td>Nine-Year Core Study Data for Sientra's FDA-Approved Round and Shaped Implants with High-Strength Cohesive Silicone Gel.</td><td>Stevens WG et al.</td><td>Aesthetic Surgery Journal</td><td>Yes</td><td></td></tr><tr><td>31</td><td>Ten-year Core Study Data for Sientra's Food and Drug Administration-Approved Round and Shaped Breast Implants with Cohesive Silicone Gel.</td><td>Stevens WG et al.</td><td>Plast Reconstr Surg</td><td>Yes</td><td></td></tr><tr><td>32</td><td>Five-year follow-up data from the U.S. clinical trial for Sientra's U.S. Food and Drug Administration-approved Silimed® brand round and shaped implants with high-strength silicone gel.</td><td>Stevens WG et al.</td><td>Plast Reconstr Surg</td><td>No</td><td>An overall risk rate for textured implant was given by implant.</td></tr><tr><td>33</td><td>Eight-Year Safety Data for Round and Anatomical Silicone Gel Breast Implants.</td><td>Duteille F et al.</td><td>Aesthetic Surgery Journal</td><td>No</td><td>Two different types of texture are studied (the texture of Eurosilicone round implant and the texture of Eurosilicone anatomical implant). The</td></tr></table>
<table><tr><td></td><td></td><td></td><td></td><td></td><td>outcomes are not given separately.</td></tr><tr><td>34</td><td>Five-year Safety Data for Eurosilicone's Round and Anatomical Silicone Gel Breast Implants.</td><td>Duteille F et al.</td><td>Plast Reconstr Surg</td><td>No</td><td>Two different types of texture are studied (the texture of Eurosilicone round implant and the texture of Eurosilicone anatomical implant). The outcomes are not given separately.</td></tr><tr><td>35</td><td>Analytical investigations on elastomeric shells of new Poly Implant Prothèse (PIP) breast and from sixteen cases of surgical explantation.</td><td>Beretta G et al.</td><td>J Pharm Biomed Anal.</td><td>No</td><td>Not a clinical study</td></tr><tr><td>36</td><td>Investigation of the silicone structure in breast implants using ¹H NMR.</td><td>Formes A et al.</td><td>J Pharm Biomed Anal.</td><td>No</td><td>Not a clinical study</td></tr><tr><td>37</td><td>Prospective study comparing two brands of cohesive gel breast implants with anatomic shape: 5-year follow-up evaluation.</td><td>Niechajev I et al.</td><td>Aesthetic Plast Surg</td><td>No</td><td>Less than 500 patients</td></tr><tr><td>38</td><td>[Descriptive analysis of the various mammary implants available on European market in 2005].</td><td>Desouches C et al.</td><td>Ann Chir Plast Esthet.</td><td>No</td><td>Not a clinical study</td></tr><tr><td>39</td><td>Critical review of additive mastoplastic with Arion hydrogel prosthesis.</td><td>Gatti A</td><td>Aesthetic Plast Surg</td><td>No</td><td>Not a clinical study</td></tr></table>
<table><tr><td>40</td><td>[Comment on an article: "Deflation of breast implants, pre-filled with saline or hydrogel. Results and analysis of a series of 650 treated patients" by L. Soubirac, E. Jougla, L. Hezard, J.L. Grolleau, J.P. Chavoin. Ann Chir Plast Esthet 47 (2002) 273-279].</td><td>Arion H</td><td>Ann Chir Plast Esthet.</td><td>No</td><td>Not a clinical study</td></tr><tr><td>41</td><td>[Carboxymethylcellulose hydrogel-filled breast implants. Our experience in 15 years].</td><td>Arion H</td><td>Ann Chir Plast Esthet.</td><td>No</td><td>Not a clinical study</td></tr><tr><td>42</td><td>[On breast implants].</td><td>Arion H</td><td>Ann Chir Plast Esthet.</td><td>No</td><td>Not a clinical study</td></tr><tr><td>43</td><td>[Statistics and breast implants].</td><td>Arion H</td><td>Ann Chir Plast Esthet.</td><td>No</td><td>Not a clinical study</td></tr><tr><td>44</td><td>[On breast implants].</td><td>Arion H</td><td>Ann Chir Plast Esthet.</td><td>No</td><td>Not a clinical study</td></tr><tr><td>45</td><td>[Siliconomas].</td><td>Arion H</td><td>Ann Chir Plast Esthet.</td><td>No</td><td>Not a clinical study</td></tr><tr><td>46</td><td>[Treatment of mammary hypoplasia with Arion prosthesis].</td><td>Kari P</td><td>Maroc Med.</td><td>No</td><td>Not a clinical study</td></tr><tr><td>47</td><td>Comment on: " Carboxymethyl cellulose (CMC) hydrogels used to fill breast implants: a 15-year experience" by H. Arion</td><td>Sharpe DT</td><td>European Journal of Plastic Surgery</td><td>No</td><td>Not a clinical study</td></tr><tr><td>48</td><td>Five-Year Safety Data for More than 55,000 Subjects following Breast Implantation: Comparison of Rare Adverse Event Rates with Silicone Implants versus National Norms and Saline Implants.</td><td>Singh Net al.</td><td>Plast Reconstr Surg</td><td>No</td><td>No rate of capsular contracture reported</td></tr><tr><td>49</td><td>Novel Approach for Maximizing Follow-Up in Cosmetic Surgery</td><td>Mueller MA et al.</td><td>Plast Reconstr Surg</td><td>No</td><td>No safety data reported</td></tr></table>
<table><tr><td></td><td>Clinical Trials: The Ideal Implant Core Trial Experience.</td><td></td><td></td><td></td><td></td></tr><tr><td>50</td><td>Risk Factor Analysis for Capsular Contracture, Malposition, and Late Seroma in Subjects Receiving Natrelle 410 Form-Stable Silicone Breast Implants.</td><td>McGuire P et al.</td><td>Plast Reconstr Surg</td><td>No</td><td>No Kaplan-Meier risk given</td></tr><tr><td>51</td><td>Prospective Analysis of Primary Breast Augmentation on Body Image Using the BREAST-Q: Results from a Nationwide Study.</td><td>Alderman A</td><td>Plast Reconstr Surg</td><td>No</td><td>No safety data</td></tr><tr><td>52</td><td>Natrelle Silicone Breast Implant Follow-Up Study: Demographics, Lifestyle, and Surgical Characteristics of More Than 50,000 Augmentation Subjects</td><td>Singh N et al.</td><td>Plast Reconstr Surg</td><td>No</td><td>No safety data</td></tr><tr><td>53</td><td>Natrelle 410 Extra-Full Projection Silicone Breast Implants: 2-Year Results from Two Prospective Studies</td><td>Cordeiro PG et al.</td><td>Plast Reconstr Surg</td><td>No</td><td>No augmentation patient</td></tr><tr><td>54</td><td>Style 410 highly cohesive silicone breast implant core study results at 3 years.</td><td>Bengtson BP et al.</td><td>Plast Reconstr Surg</td><td>Yes</td><td></td></tr><tr><td>55</td><td>Natrelle style 410 form-stable silicone breast implants: core study results at 6 years</td><td>Maxwell GP et al.</td><td>Aesthet Surg J</td><td>Yes</td><td></td></tr><tr><td>56</td><td>Late seromas after breast implants: theory and practice.</td><td>Spear SL et al</td><td>Plast Reconstr Surg</td><td>No</td><td>No rate of capsular contracture reported</td></tr></table>
<table><tr><td>57</td><td>Natrelle saline-filled breast implants: a prospective 10-year study</td><td>Walker PS et al.</td><td>Aesthet Surg J</td><td>No</td><td>Only saline-filled breast implants were used</td></tr><tr><td>58</td><td>A prospective, multi-center study of psychosocial outcomes after augmentation with natrelle silicone-filled breast implants</td><td>Murphy DK et al.</td><td>Ann Plast Surg</td><td>No</td><td>Less than 500 patients</td></tr><tr><td>59</td><td>Breast augmentation motivations and satisfaction: a prospective study of more than 3,000 silicone implantations</td><td>Gladfelter J et al.</td><td>Plast Surg Nurs</td><td>No</td><td>No safety data</td></tr><tr><td>60</td><td>Ten-year results from the Natrelle 410 anatomical form-stable silicone breast implant core study</td><td>Maxwell GP et al.</td><td>Aesthet Surg J</td><td>Yes</td><td></td></tr><tr><td>61</td><td>Inamed silicone breast implant core study results at 6 years</td><td>Spear SL et al.</td><td>Plast Reconstr Surg</td><td>No</td><td>59% of smooth implants were used</td></tr><tr><td>62</td><td>Prevalence of rupture in inamed silicone breast implants</td><td>Hedén P et al.</td><td>Plast Reconstr Surg</td><td>No</td><td>Less than 500 patients</td></tr><tr><td>63</td><td>A modification of the parameter system and surgical techniques with McGhan anatomical implants for breast augmentation</td><td>Gao J et al.</td><td>Chinese Journal of Aesthetic Medicine</td><td>No</td><td>Less than 500 patients</td></tr><tr><td>64</td><td>Two Stage Breast Reconstruction with McGhan LV Expanders and McGhan 363 LF Implants: A Review of 82 Breast Reconstructions in 62 Consecutive Patients</td><td>Scott Gr</td><td>Congress communication</td><td>No</td><td>Less than 500 patients</td></tr><tr><td>65</td><td>Discussion: Risk Factor Analysis for Capsular Contracture, Malposition, and Late Seroma in Subjects Receiving Natrelle 410 Form-Stable Silicone Breast Implants</td><td>Disa JJ et al.</td><td>Plast Reconstr Surg</td><td>No</td><td>Not a clinical study</td></tr></table>
<table><caption>Table 8: Selected and non-selected articles through the scientific database search</caption><tr><td>66</td><td>Comparison of the Explantation Rate of Poly Implant Prothèse, Allergan, and Pérouse Silicone Breast Implants within the First Four Years after Reconstructive Surgery before the Poly Implant Prothèse Alert by the French Regulatory Authority</td><td>Leduey A et al.</td><td>International Journal of Breast Cancer</td><td>No</td><td>Less than 500 patients</td></tr><tr><td>67</td><td>Allergan Style 410 Implants for Breast Reconstruction: A Prospective Study in Efficacy, Safety, and Symmetry</td><td>Unger JG et al.</td><td>Plast Reconstr Surg</td><td>No</td><td>Less than 500 patients</td></tr><tr><td>68</td><td>Risk factor analysis for capsular contracture, malposition, and late seroma in subjects receiving Natrelle 410 form-stable silicone breast implants</td><td>Quinlan CS et al.</td><td>Plast Reconstr Surg</td><td>No</td><td>Not a clinical study</td></tr><tr><td>69</td><td>Reply: Risk Factor Analysis for Capsular Contracture, Malposition, and Late Seroma in Subjects Receiving Natrelle 410 Form-Stable Silicone Breast Implants</td><td>McGuire P</td><td>Plast Reconstr Surg</td><td>No</td><td>Not a clinical study</td></tr></table>

### 1.5.2.3. RETRIEVED CLINICAL DATA CATEGORIZED BY BREAST IMPLANT SURFACES

On the basis of the mentioned selection criteria, 9 articles were retained [1, 3, 7, 29, 30, 31, 54, 55, 60].<fnref n="1" /> Actually, these articles correspond to three different Cohort studies (currently completed). Basically, the Cohort studies are one of the Pre-Market Clinical Studies that a breast implant manufacturer must lead to obtain the FDA approval since the moratorium. These studies have a similar design:

* Observational, prospective and multicenter

<footnote n="1">¹ The references between square brackets correspond to the articles of the Table 8.</footnote>
* Nonrandomized

* 10-year follow-up

* Centers located in the USA

* Outcome computed with the Kaplan-Meier methodology

* Annual visits

* 4 cohorts of patients: primary augmentation, revision augmentation, primary reconstruction and revision reconstruction

Thus, [1, 3, 7] reported the outcomes of the Cohort study led by Mentor on Contour Profile Gel implants at 2 years, 9 years and 10 years of follow-up. Actually, Caplin et al. [3] reported the safety data of two cohort studies led by Mentor: the Cohort study on Contour Profile Gel implants and the one on Silicone MemoryGel implants. Only the results of the first study were retained in the analysis because the second study encompassed smooth and textured implants. The clinical outcomes on Sientra round and shaped implants were published at 8 years, 9 years and 10 years [29, 30, 31]. Likewise, Allergan published the results on Natrelle 410 anatomical implants at 3 years, 6 years and 10 years [54, 55, 60].

Moreover, the implants studied in the three Cohort studies belong to the fifth-generation and more particularly are anatomically shaped for the Allergan- and Mentor-sponsored studies. In the Sientra study, approximately 10% of the implants were anatomically shaped. Thus, the outcome comparison between the three studies is all the more relevant as study design and implant characteristics are similar.

All the implants of the Cohort studies promoted by Allergan and Mentor were Biocell-textured and Siltex-textured respectively. Regarding the Sientra Cohort study, 53% of the implants were smooth. However, the cumulative risk of capsular contracture was given separately for the cohort of patients with smooth implants and for the cohort of patients with textured implants (TRUE texture). Thus, a cumulative risk of capsular contracture of patients with Biocell-textured, Siltex-textured, TRUE texture-textured and Sientra smooth implants was provided by these three Cohort studies. Maxwell et al. [60] reported the risk of capsular contracture in the Primary Augmentation cohort of the Allergan-sponsored Cohort study at 4 weeks, 6 months, 1 year, 2 years, 3 years, 4
years, 5 years, 6 years, 7 years, 8 years, 9 years and 10 years of follow-up. For comparison purpose between the different types of texture, only the risks at 2 years, 3 years, 6 years, 8 years, 9 years and 10 years were retained. However, some discrepancies were noted between the rates at 3 years and 6 years given by Maxwell et al. [60] and the ones given by Bengtson et al. [54] and Maxwell et al. [55]. The interim and the 10-year outcomes are reported in the Table 9 for the 4 different types of surface studies in the selected articles.

<table><caption>Table 9: Cumulative risks of capsular contracture of different breast implant surfaces retrieved from the scientific database search</caption><thead><tr><th>Follow-up</th><th>2 years</th><th>3 years</th><th>6 years</th><th>8 years</th><th>9 years</th><th>10 years</th></tr></thead><tbody><tr><td>Siltex [1, 3, 7]</td><td>0.8</td><td></td><td></td><td></td><td>3.4</td><td>3.6</td></tr><tr><td>TRUE Texture [29, 30, 31]</td><td></td><td></td><td></td><td>7.3</td><td>8</td><td>9</td></tr><tr><td>Silimed smooth [29, 30, 31]</td><td></td><td></td><td></td><td>15.8</td><td>16.6</td><td>17.5</td></tr><tr><td>Biocell [60]</td><td>1.7</td><td>2.1</td><td>5.2</td><td>6.8</td><td>7.9</td><td>9.2</td></tr></tbody></table>

Moreover, on the basis of these cumulative risks, Stevens et al. demonstrated a statistically reduced risk of capsular contracture with Sientra textured implants compared to Sientra smooth implants at 8 years, 9 years and 10 years (p=<0.0001, p=0.0002, p=0.0007 respectively). [29, 30, 31]

More precisely, in the Mentor-sponsored Cohort study, the risk of capsular contracture at 10 years of follow-up among primary augmentation patients with a Siltex-textured implant with subglandular placement (7.7%) compared to those with submuscular placement (3.05%) was not significantly different (p=0.0625 according to the log-rang test). However, by controlling prior occurrence of a hematoma or seroma and clinical site with a proportional hazards regression model, the capsular contracture rate with subglandular placement was significantly higher (hazard ratio=3.1). [7]

A single case of BIA-ALCL was reported from the three Cohort studies. [60] This case was declared on Biocell-textured implants. In 2015, Brody et al. theorized that some surface processing of breast implant (called texture) might play an important role: they noted that where the clinical history was known, the patient had received at least one
textured surface breast device. (35) More and more clinical evidences are in favor of
an association between Biocell and BIA-ALCL. (110)

1.5.3. CLINICAL EVALUATION OF A POTENTIAL LINK BETWEEN SOME TYPES OF TEXTURES AND THE INCIDENCE OF BIA-ALCL

As mentioned previously, to establish that the risk of BIA-ALCL is potentially impacted
by some types of texture, a selective literature review of compiled report cases was
led. For each case, the characteristics of breast prostheses implanted at the time of
BIA-ALCL diagnosis were extracted. If the patients have had beforehand other
implants and if the implants were identified, these prior implants were also taken into
account in the analysis and represent the implant history of the patients. The cases
were retrieved from different sources (federal database, literature review, large
clinical studies).

1.5.3.1. METHODOLOGY OF THE CLINICAL EVALUATION VIA LITERATURE AND FEDERAL DATABASE REVIEW

The details of the literature review are specified below.

* Date of the research

The research was performed on February, 11th 2019.

- Literature sources used to identify articles

Pubmed was used to identify literature data.

* Selection criteria used to choose articles

The selection criteria were the following:

o article in English or in French

o All the BIA-ALCL cases obtained through a chosen clinical source must be reported over a given period of time and a precise geographical location (i.e. without restriction to a texture or a manufacturer). If several articles used the same methodology and covered the same geographical location, the most recent article will be retained.
* The type of texture or the manufacturer must be known for most of the reported BIA-ALCL cases (commercial name or texturing process given). If detailed in the article or in the Supplementary Materials of the article, the characteristics of prior implants might be taken into account.

* full text available

* no Acellular Dermal Mesh (ADM) used

### Database search details

A search on Medline (Pubmed) with the term: (Breast Implant-Associated Anaplastic Large Cell Lymphoma OR BIA-ALCL OR breast-ALCL) AND (incidence OR incidences OR prevalence OR case OR cases OR risk OR risks) AND (database OR databases OR registry OR registries OR series) was implemented.

If the previously mentioned regulatory agencies reported the cases per manufacturer (or per type of texture), these statistics were also taken into account in the analysis.

The workflow of the search is schematically represented in the Figure 5.
<figure><img src="image_7.png" /><figcaption>Figure 5: Workflow for the selection of articles from the scientific databases</figcaption></figure>

1.5.3.2. LIST OF THE SELECTED AND NON-SELECTED ARTICLES IN THE LITERATURE REVIEW

After exclusion of two articles (one written in Swedish and one duplicate), 20 articles were identified.
<table><thead><tr><td>N°</td><td>Study title</td><td>Author</td><td>Journal</td><td>Selected / Not Selected</td><td>Reason for non-selection</td></tr></thead><tbody><tr><td>1</td><td>Breast Implant-Associated Lymphoma.</td><td>Kricheldorff J et al.</td><td>Dtsch Arztebl Int.</td><td>Yes</td><td></td></tr><tr><td>2</td><td>Peripheral T-Cell Lymphomas: Incorporating New Developments in Diagnostics, Prognostication, and Treatment Into Clinical Practice-PART 1: PTCL-NOS, FTCL, AITL, ALCL.</td><td>Zing NPC et al.</td><td>Oncology (Williston Park)</td><td>No</td><td>Not a case report</td></tr><tr><td>3</td><td>Breast Implants and the Risk of Anaplastic Large-Cell Lymphoma in the Breast.</td><td>de Boer M et al.</td><td>JAMA Oncol.</td><td>Yes</td><td></td></tr><tr><td>4</td><td>22 Cases of Breast Implant-Associated ALCL: Awareness and Outcome Tracking from the Italian Ministry of Health.</td><td>Campanale A et al.</td><td>Plast Reconstr Surg.</td><td>No</td><td>"The Manufacturers and the Codes of the Implanted devices have not been disclosed because they are covered by confidentiality agreements and they are not relevant for the purposes of this study."</td></tr><tr><td>5</td><td>Breast Implant-Associated Anaplastic Large Cell Lymphoma: A Systematic Review.</td><td>Leberfinger AN et al.</td><td>JAMA Surg.</td><td>No</td><td>The types of texture are not reported</td></tr></tbody></table>
<table><tr><td>6</td><td>Breast Implant-Associated Anaplastic Large-Cell Lymphoma in a Transgender Woman.</td><td>De Boer M et al.</td><td>Aesthet Surg J.</td><td>No</td><td>Report of one case</td></tr><tr><td>7</td><td>Breast implant capsule-associated squamous cell carcinoma: a report of 2 cases.</td><td>Olsen DL et al.</td><td>Hum Pathol.</td><td>No</td><td>Report of two carcinoma cases</td></tr><tr><td>8</td><td>Breast implant associated anaplastic large cell lymphoma: The UK experience. Recommendations on its management and implications for informed consent.</td><td>Johnson L et al.</td><td>Eur J Surg Oncol.</td><td>Yes</td><td></td></tr><tr><td>9</td><td>Breast Implant-Associated Anaplastic Large Cell Lymphoma in Australia and New Zealand: High-Surface-Area Textured Implants Are Associated with Increased Risk.</td><td>Loch-Wilkinson A et al.</td><td>Plast Reconstr Surg.</td><td>Yes</td><td></td></tr><tr><td>10</td><td>Primary Breast Lymphoma in the United States: 1975-2013.</td><td>Thomas A et al.</td><td>J Natl Cancer Inst.</td><td>No</td><td>No details on the implants</td></tr><tr><td>11</td><td>NCCN Consensus Guidelines for the Diagnosis and Management of Breast Implant-Associated Anaplastic Large Cell Lymphoma.</td><td>Clemens MW et al.</td><td>Aesthet Surg J.</td><td>No</td><td>Not a case report</td></tr><tr><td>12</td><td>Global Adverse Event Reports of Breast Implant-Associated ALCL: An International Review of 40 Government Authority Databases.</td><td>Srinivasa DR et al.</td><td>Plast Reconstr Surg.</td><td>No</td><td>Only the manufacturers of the cases declared to the US MAUDE</td></tr></table>
<table><tr><td></td><td></td><td></td><td></td><td>database were reported.</td></tr><tr><td>13</td><td>U.S. Epidemiology of Breast Implant-Associated Anaplastic Large Cell Lymphoma.</td><td>Doren EL et al.</td><td>Plast Reconstr Surg.</td><td>Yes</td></tr><tr><td>14</td><td>Lymphomas Associated with Breast Implants: A Review of the Literature.</td><td>Rupani A et al.</td><td>Aesthet Surg J.</td><td>No</td></tr><tr><td>15</td><td>Anaplastic large-cell lymphoma associated with breast implants: a unique entity within the spectrum of peri-implant effusions.</td><td>Chai SM et al.</td><td>Diagn Cytopathol.</td><td>No</td></tr><tr><td>16</td><td>Implant-associated anaplastic large cell lymphoma of the breast: Insight into a poorly understood disease.</td><td>Weathers WM et al.</td><td>Can J Plast Surg.</td><td>No</td></tr><tr><td>17</td><td>Anaplastic large cell lymphoma occurring in association with breast implants: review of pathologic and immunohistochemical features in 103 cases.</td><td>Taylor CR et al.</td><td>Appl Immunohistochem Mol Morphol.</td><td>No</td></tr><tr><td>18</td><td>Risk of lymphoma in women with breast implants: analysis of clinical studies.</td><td>Largent J et al.</td><td>Eur J Cancer Prev</td><td>No</td></tr></table>
<table><caption>Table 10: Selected and non-selected articles through scientific database search</caption><tr><td>19</td><td>Breast implant-associated, ALK-negative, T-cell, anaplastic, large-cell lymphoma: establishment and characterization of a model cell line (TLBR-1) for this newly emerging clinical entity.</td><td>Lechner MG et al.</td><td>Cancer.</td><td>No</td><td>Not a case report</td></tr><tr><td>20</td><td>Anaplastic large-cell lymphoma in women with breast implants.</td><td>de Jong D et al.</td><td>JAMA.</td><td>No</td><td>A more recent case report using the same methodology and on the same country has been already retained (3).</td></tr></table>

### 1.5.3.3. RETRIEVED CLINICAL DATA CATEGORIZED BY BREAST IMPLANT SURFACES OR MANUFACTURERS

Only two regulatory agencies (ANSM and Health Canada) provided a detail of BIA-ALCL cases per manufacturer. (Table 11) ANSM was able to retrieve the prior implants for each case, which corresponded to 80 implants.
<table><caption>Table 11: BIA-ALCL cases per manufacturer reported by the French regulatory agency (ANSM) and by the Canadian regulatory agency (Health Canada)</caption><thead><tr><th rowspan="2"></th><th colspan="2">ANSM</th><th colspan="2">Health Canada</th></tr><tr><th>Through the implant history of the patients</th><th>Implant on diagnosis</th><th>Implant on diagnosis</th></tr></thead><tbody><tr><td>McGhan/Inamed/ Allergan</td><td>47</td><td>32</td><td>18</td></tr><tr><td>Arion</td><td>2</td><td>2</td><td></td></tr><tr><td>Cereplas</td><td>2</td><td>2</td><td></td></tr><tr><td>Eurosilicone</td><td>1</td><td>1</td><td></td></tr><tr><td>Mentor</td><td>2</td><td>1</td><td>2</td></tr><tr><td>Perouse-Plastie</td><td>2</td><td>1</td><td></td></tr><tr><td>PIP</td><td>5</td><td>1</td><td></td></tr><tr><td>Polytech</td><td>1</td><td>1</td><td></td></tr><tr><td>Silimed</td><td>2</td><td>1</td><td>1</td></tr><tr><td>Unknown</td><td>16</td><td>8</td><td>1</td></tr></tbody></table>

However, these data are not exploitable for two reasons.

Firstly, they are absolute (i.e. not relative to the number of implanted prostheses in France or in Canada or to the sales data of the different manufacturers). This point is particularly important for a worldwide comparison because all the manufacturers are not present in all the countries or their market share may be different. Thus, in France PIP (April 2010), Perouse-Plastie (end of 2011), Cereplas (February 2014), and Silimed (2015) do not sell implant anymore. In Canada, only Allergan, Mentor and Ideal Implant implants were approved.

Secondly, the commercial names of the texture are unknown and some manufacturers (such as Allergan and Arion) commercialize several types of texture. To address this point, the LYMPHOPATH network presented during the ANSM-mandated public audition in February 2019 the most updated data summarized in the Table 12, in which the types of texture were collected as far as possible. The table takes into
account all the prior implants of each case confirmed by the network (n=46). The data are given per implant as well as per patient.

<table><caption>Table 12: BIA-ALCL cases per type of breast implant surface reported by the LYMPHOPATH network</caption><thead><tr><th rowspan="2"></th><th rowspan="2">Manufacturer</th><th rowspan="2">Commercial name of texture</th><th colspan="2">Through the implant history of the patients</th></tr><tr><th>Per implant (n=136)</th><th>Per patient (n=46)</th></tr></thead><tbody><tr><td rowspan="6">Textured</td><td rowspan="3">McGhan/Allergan</td><td>Biocell</td><td>58</td><td>32</td></tr><tr><td>Microcell</td><td>1</td><td>1</td></tr><tr><td>Unknown</td><td>9</td><td>5</td></tr><tr><td>PIP</td><td></td><td>3</td><td>2</td></tr><tr><td>Mentor</td><td>Siltex</td><td>2</td><td>1</td></tr><tr><td>Other brands</td><td>Microtextured*</td><td>5</td><td>3</td></tr><tr><td></td><td></td><td>Unknown</td><td>6</td><td>4</td></tr><tr><td>PU-coated</td><td>Polytech</td><td></td><td>2</td><td>1</td></tr><tr><td>Smooth</td><td>All brands</td><td></td><td>2</td><td>1</td></tr><tr><td>Unknown</td><td></td><td></td><td>48</td><td>21</td></tr></tbody></table>

*refer to commercial denominations

The FDA did not detail the surface characteristics on BIA-ALCL cases identified. However, for the first time, known cases in patients with only smooth-surface breast implants were reported. (https://www.youtube.com/watch?v=wpdkXMEj60U)

On the basis of the mentioned selection criteria of the literature review, 5 articles were retained [1, 3, 8, 9, 13].<fnref n="2" />

Doren et al. [13] performed a retrospective review of the unpublished cases diagnosed at their institution and the cases the authors were able to pathologically confirm from the literature from 1996 to 2015 in the USA. Thus, 100 cases were identified

<footnote n="2">² The references between square brackets correspond to the articles of the Table 10.</footnote>
and confirmed. The texturing processes of the implants on diagnosis were reported. As
only Allergan commercialized salt-loss-textured implants in the USA and as only Mentor
sold imprint-stamping-textured implants in the USA, the identification of the type of
texture was straight-forward. Based on annualized sales data of breast implants in the
USA, the authors were the first to provide an incidence rate of BIA-ALCL per type of
texture. Thus, the overall incidence rates for salt-loss-textured implant and for imprint-
stamping-textured implant were estimated at 1.87 per 1 million person-years and at
0.33 per 1 million person-years respectively. The incidence was significantly lower with
imprint-stamping-textured implant (p<0.001).

A joint Australia and New Zealand task force was formed between members of the plastic surgery, breast oncology, hematology and oncology, and cosmetic surgical societies to screen all the BIA-ALCL cases between 2007 and August 2016 [9]. Thus, 55 cases were identified. All implant histories of these cases (n=75 implants) were obtained. 79% of implants involved in the reported cases were either Biocell-textured or PU-coated. A further statistical analysis based on the odds ratio was led by type of texture. Thus, the risk for developing BIA-ALCL was 14.11 times higher for Biocell and 10.84 times higher with PU coating as compared with Siltex texture. A Kaplan-Meier analysis determined that the risk with Biocell was particularly important from the 8th year of exposure. Moreover, the task force allowed the authors to release the sales data of the three major implant manufacturers in the region (Mentor, Allergan and Silimed) between 1999 and 2015 (Nagor did not provide sales data) and therefore to compute implant-specific risk for patients exposed to single implant texture type. Thus, the cases of BIA-ALCL per number of implantations were estimated at one in 3817 for Biocell texture, at one in 7788 for PU coating and at one in 60631 for Siltex texture, which are the highest reported incidences until now. (69) The risk with PU-coated implants was likely underestimated because the manufacturer of this type of implant (Silimed) obtained Australian regulatory approval only in 2008.

23 cases of BIA-ALCL were reported by Johnson in the UK between 2012 and 2016 [8].
The histories of implantation were known for 18 patients thanks to a close collaboration
between the Association of Breast Surgery (ABS), British Association of Plastic,
Reconstructive and Aesthetic Surgeons (BAPRAS) and the British Association of Aesthetic Plastic Surgeons (BAAPS) networks.

De Boer et al. [3] identified 32 cases of BIA-ALCL in the Netherlands through the population-based nationwide Dutch pathology registry between 1990 and 2016. Of the 28 patients with BIA-ALCL with known implant type, 23 (82%) had “macrotextured” implants on diagnosis. Moreover, the complete implant history was detailed for the 32 cases in the Supplementary Online Content. The authors added that “only 45% of all implants sold in the Netherlands in 2010 to 2015 were macrotextured”. Implant-specific risk was not performed because “our sales data lack historical information on market shares before 2010, as a result of bankruptcy or changing distributors with loss of product data files.”

Kricheldorff et al. [1] reported the cases in Germany. Only 7 cases were identified by personal inquiry to the Federal Institute for Drugs and Medical Devices (BfArM), the German Society of Plastic, Reconstructive, and Aesthetic Surgeons (Deutsche Gesellschaft der Plastischen, Rekonstruktiven und Ästhetischen Chirurgen, DGPRÄC), and the German Society for Gynecology and Obstetrics (Deutsche Gesellschaft für Gynäkologie und Geburtshilfe, DGGG). The implant history was known for 6 cases.

In each of the retained articles and federal databases, the type of texture present on the implant on diagnosis and on all the prior implants of each reported case was identified, counted and summarized in the Table 13. The types of texture, which were never sold in the corresponding countries to our knowledge, were also mentioned. The hypotheses regarding the pathogenesis of the BIA-ALCL given in each article were added in the table.

From the hypotheses, the authors seemed to agree with a multifactorial etiology. Among the 5 retained articles, the “chronic inflammation” was explicitly reported in 4 articles. [1, 3, 8, 13] The fifth article [9] used a synonymous term: “chronic antigen stimulation”. Consistently, chronic inflammation related to repeated antigenic stimulation has been noted as a factor triggering lymphocyte activation, recruitment, transformation and ultimately lymphomagenesis. (111-115) Once activated, the T
lymphocytes will differentiate into different subsets with different antigen specificities. Thus, the T-helper 1 cells are specific against intracellular viral and bacterial pathogens, T-helper 17 cells are involved in mucosal immunity and autoimmune disorders and T-regulatory cells inhibit proinflammatory T cells. (116)

Different reasons were proposed to elicit this malignant host immune response: the "biofilm" (which was also reported by the authors as a "proliferation" of "adherent bacteria" on the implant surface) mentioned in 4 articles [1, 3, 9, 13], the particulate shedding of the implant surface reported in 3 articles [1, 3, 13] and an eventual chemical toxicity [3, 13]. A genetic predisposition of patients for the risk of lymphoma was also suggested [3, 9, 13].

Even though an association was demonstrated in some models (see the section 1.6 "Biological models"), these malignant triggers remain theoretical because a causative link has not been demonstrated yet. Thus, although the biofilm was the most reported hypothesis, the biological mechanism of tumorigenesis remains unelucidated. Some authors mitigated the bacterial species identified in BIA-ALCL capsule specimens because they were not properly compared with a relevant control microbiome, which is quite challenging. (117) Myckatyn et al. even suggested that the clusters of Ralstonia spp. identified by Hu et al. (64) would be purely "opportunistic" and that the stimulus would be actually bacterial superantigens, such as the lipopolysaccharide coat of bacteria. (118) Regarding the silicone antigenic hypothesis, Prantl et al. cautioned against the exact origin of the silicone particles or leachable: "It remains unclear whether these silicone structures represent friction particles from the surface of the implant or particles of implant filler." (119)
<table><thead><tr><th></th><th>UK</th><th>Australia/<br>New-<br>Zealand</th><th>Netherlands</th><th>USA</th><th>Germany</th><th>France</th></tr></thead><tbody><tr><td></td><td>Johnson [8]</td><td>Loch-<br>Wilkinson [9]</td><td>De Boer [3]</td><td>Doren [13]</td><td>Kricheldorff [1]</td><td>LYMPHOP<br>ATH<br>database</td></tr><tr><td></td><td>Implant<br>on<br>diagnosis</td><td>Through<br>the<br>implant<br>history of<br>the<br>patients</td><td>Implant<br>on<br>diagnosis</td><td>Through<br>the<br>implant<br>history of<br>the<br>patients</td><td>Implant<br>on<br>diagnosis</td><td>Through<br>the<br>implant<br>history of<br>the<br>patients</td></tr><tr><td>Biocell</td><td>10</td><td>19</td><td>44</td><td>22</td><td>23</td><td>46</td><td>3</td><td>6</td><td>58</td></tr><tr><td>CRISTALLINE<br>Microtextured</td><td></td><td></td><td>0</td><td>2</td><td>2</td><td>never sold</td><td></td><td></td><td></td></tr><tr><td>Nagotex</td><td>3</td><td>4</td><td>5</td><td>1</td><td>1</td><td>never sold</td><td></td><td></td><td></td></tr><tr><td>TRUE Texture</td><td></td><td></td><td>0</td><td></td><td></td><td></td><td>1</td><td>1</td><td></td></tr><tr><td>POLYtxt</td><td></td><td></td><td>0</td><td></td><td></td><td>never sold</td><td>1</td><td>1</td><td></td></tr><tr><td>Siltex</td><td>0</td><td>2</td><td>5</td><td>1</td><td>1</td><td>8</td><td>1</td><td>1</td><td>2</td></tr></tbody></table>
<table><tr><td>Microcell</td><td>1</td><td>1</td><td>0</td><td></td><td></td><td></td><td></td><td>1</td></tr><tr><td>Sebbin<br/>Microtextured</td><td></td><td></td><td>0</td><td>1</td><td>1</td><td>never sold</td><td></td><td></td></tr><tr><td>Smooth implant*</td><td></td><td></td><td>4</td><td></td><td></td><td></td><td></td><td>2</td></tr><tr><td>VELVET</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>3</td></tr><tr><td>PU-coated implant*</td><td>3</td><td>3</td><td>15</td><td></td><td></td><td></td><td></td><td>2</td></tr><tr><td>Unknown</td><td>1</td><td>5</td><td>0</td><td>4</td><td>16</td><td>49</td><td></td><td>1</td><td>68</td></tr></table>
<table><tr><td>Hypothesis of pathogenesis</td><td>"The aetiology of this disease remains unclear and, despite the growing body of evidence implicating chronic inflammation within the capsular biofilm, some authors advise caution in drawing conclusions until science catches up with this unusual entity."</td><td>"We propose that the higher surface area acts as a passive conduit for the growth and proliferation of bacteria, which, once they reach a threshold, cause ongoing immune activation and transformatio</td><td>"So far, various, not mutually exclusive causal factors have been suggested. Specifically, a local inflammatory response, elicited by silicone derived products or specific bacterial species adherent to the prosthesis surface (biofilm) may play a role, possibly via an auto-immune response. Toxic products related to the production of breast implants have been implicated as</td><td>"Some theories implicate the immune system response to chronic inflammation, likely induced by silicone particulate, modified silicone, or bacterial antigen in a genetically susceptible patient"</td><td>"A connection with implant-induced chronic inflammation has been discussed, as has genetic susceptibility in the sense of severe reactive dysplasia as a response to chronic inflammation. Other suspected causes include particle erosion of the implants, a subclinical biofilm, or chronic T-cell stimulation."</td></tr></table>
n in susceptible hosts over time. The contamination of textured implants with a higher surface area by bacteria leading to chronic antigen stimulation in genetically susceptible hosts over a prolonged period may

direct mutagens. Whether certain groups of women have a genetically determined increased risk to develop lymphoma when exposed to breast implants, eg, via a genetically determined altered or exaggerated local immunological response, remains hypothetical."
<table><caption>Table 13: BIA-ALCL cases per type of breast implant surface and hypotheses of pathogenesis retrieved from scientific and federal database search</caption><tr><td>result in<br>transformation<br>of T cells<br>into breast<br>implant-<br>associated<br>ALCL."</td></tr></table>

* As we suppose non-significant differences between the different smooth implants and between the different PU-coated implants sold by the different manufacturers, the latter were not mentioned for these cases. (91)
Two thirds of BIA-ALCL diagnoses were clinically characterized by an effusion (or seroma) in the breast implant pocket. Benign late seroma associated with breast implant were also reported. Similarly with BIA-ALCL, double capsules were predominantly observed on Biocell-textured implants. (120)

### 1.5.4. CLINICAL EVALUATION OF A POTENTIAL LINK BETWEEN SOME TYPES OF TEXTURES AND THE INCIDENCE OF LATE SEROMA OR DOUBLE CAPSULE

The previously described methodology was applied for late seroma and double capsules.

A similar search on Medline (Pubmed) with the term: ("double capsule") AND ("breast implant" OR "breast implants") AND (incidence OR incidences OR prevalence OR case OR cases OR risk OR risks) AND (database OR databases OR registry OR registries OR series) was implemented.

No article was identified.

Then, a second search on Medline (Pubmed) with the term: ("late seroma") AND ("breast implant" OR "breast implants") AND (incidence OR incidences OR prevalence OR case OR cases OR risk OR risks) AND (database OR databases OR registry OR registries OR series) was performed.

Among the two articles identified, the first was excluded because ADM was used (121) and the second reported between 2002 and 2011 only cases with Biocell-textured prostheses and did not mention cases on other types of texture (65).

As a result of the literature and federal database review, chronic inflammation is of primer importance in the BIA-ALCL onset and different causative hypotheses were proposed, such as biofilm-mediated or debris-mediated inflammation. However, in a clinical evidence-based medicine, biological demonstration of these hypotheses must be provided. Thus, different biological models were designed for this purpose.
Different biological models were proposed to analyse the biological reactions, in term of host tissues, host cells and microbiome, occurring around the breast implant: *in vivo* model, *in vitro* model and *ex vivo* model.

### 1.6.1. IN VIVO MODELS

*In vivo* models consisted of implanting custom-made breast implants in animals and characterizing the surrounding biological reactions. Further studies were also led to determine whether these biological reactions were modulated by some species or molecules.

The first *in vivo* model was developed in rabbits by Lilla *et al.*, who evaluated the in situ mobility of plain silicone, perforated silicone backed, Dacron-backed and PU-covered prostheses. (122) In situ mobility was assessed as the distance along which the implant could be moved under the skin. Thus, Dacron-backed implants were significantly less mobile than the plain ones and PU-covered implants were much less mobile than the average of all the others. Barone *et al.* also used rabbits to quantify some biomechanical parameters (such as the stiffness and the energy absorption) of the capsule from in situ measurements of pressure and volume. (99) The capsules facing the Biocell-textured and PU-coated expanders had a significantly lower stiffness and a significantly higher energy absorption than with a smooth expander implanted during 6 months. McLean *et al.* retrieved from rats host tissues in contact with breast implant samples, and performed an immunostaining with antibodies targeting the enzyme cyclooxygenase-2 (COX-2). (123) This enzyme is of particular interest because it mediates the inflammatory cascade. Cytoplasmic COX-2 expression was identified in endothelial cells, macrophages and fibroblasts from the 4th day to the 80th day after implantation. Moyer *et al.* studied whether some characteristics of breast implant other than surface (such as gel viscosity or barrier layer) elicited capsular contracture in swine. (75) Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) and tensiometry were used. The stiffness measured by dynamic compression on the implant and the capsule dissected *en bloc* was correlated with the intracapsular concentration of silicon. Moreover, whatever the generation of implants, the ruptured
implants were significantly more associated with high-grade contracture than the non-
ruptured implants at 1 month.

The *in vivo* biological reaction to implants coated by proteins of interest was also studied in a rabbit model by Marques *et al.* (124-126) The authors used mostly as implanted device a temporary expander with a sensor measuring the intracapsular pressure. The implants were either impregnated of fibrin, thrombin or blood, chitosan or sprayed of fibrin. All these studies were designed with a control group (i.e. implants without coating). A H&E-based histological analysis of the capsular tissue allowed the authors to score the intensity (absent, mild, moderate or severe) and to characterize the type (mononuclear/chronic, mixed/subacute or polymorph/acute) of the inflammatory infiltrate. The capsular thickness and architecture, such as the density and the organisation of collagen fibres, the degree of angiogenesis and the foreign body density, was highlighted by Trichrome staining. At 4 weeks, the fibrin- and thrombin-impregnated expanders as well as fibrin-sprayed expanders experienced significantly decreased intracapsular pressure compared to the control groups. A statistical analysis pointed out that for fibrin-impregnated and control groups, the determining factor for intracapsular pressure was the type of inflammation (mixed inflammation or mononuclear inflammation), whereas for the fibrin-sprayed group, the intracapsular pressure was correlated with capsular thickness. In the blood group, an increase of fibroblast densities and a decrease of angiogenesis were reported compared to the control group. A study quantified the levels of Interleukin 8 (IL8) by a microdialysate of the periprosthetic fluid by a solid-phase sandwich Enzyme-Linked ImmunoSorbent Assay (ELISA). (125) The chitosan group was significantly associated with Baker Grade III/IV, thick capsules, dense connective tissue and decreased IL-8 levels compared to the control.

*In vivo* models were also developed to analyse the impact of a deliberate inoculation of implant with a bacterial strain on the capsular architecture and inflammatory infiltrate (127), on the in situ bacterial colonization (60, 128, 129) and on the immune host response (60). Only strains of Coagulase-Negative Staphylococci, such as Staphylococcus epidermidis, were inoculated. Recently, Bergmann *et al*. quantified the capsular thickness and the thickness of the synovial-like metaplasia, the thickness
and density of parallel myofibrils, the number of layers in the capsule and the inflammatory cell number around inoculated PU-coated and textured implants in a rat model. (127) In comparison with textured implants, capsules around PU-coated implants showed significantly lower expression of parallel myofibrils, lower average thickness of synovial-like metaplasia and higher infiltration with inflammatory cells, in both contaminated and non-contaminated groups. As the only positive bacterial culture (found with PU-coated implant) had "no signs of acute infection or tendency toward positive bacterial growth", the authors hypothesized that the PU-coated implants had "no higher risk of a biofilm-dependent fibrosis". Jacombs et al. (129) and Hu et al. (60) used the pig model and a protocol combining ultra-sounds with enrichment culture established by Tamboto et al. (128) to isolate biofilm bacteria and evaluated the total number of bacteria attached to inoculated smooth or textured implants and present in capsular tissue by real-time quantitative reverse transcriptase Polymerase Chain Reaction (PCR) with the universal eubacterial primer 16S rRNA. The contracted breast capsules had 250% more bacteria than the non-contracted capsules. Moreover, a significant correlation was found between the number of bacteria attached to the implant and the Baker grade. This correlation was confirmed by standard bacterial plate culture of capsular sample. Likewise, 11-, 43- and 72-fold more bacteria were cultured on the surface of textured implants at 2, 6 and 24h respectively, compared with smooth implant. This predominance was confirmed by SEM, which highlighted a dense and mature biofilm on textured implants and a patchy biofilm on smooth implants. A quantification of the number of T-helper cell and the T-cytotoxic cell was also performed by PCR (60). All the lymphocytes were significantly more numerous on textured compared with smooth implants (63-fold increase). Immunohistochemistry with different antibodies targeting specific membrane proteins of lymphocyte phenotypes (T-cell or B-cell), confirmed T-cells represent the majority of the lymphocytic infiltrate.

In order to suggest therapeutic alternatives of bacteria-mediated complications, an immersion of implants in antimicrobial solution (composed of iodine-povidone and antibiotics), a covering of implants with antibiotic-impregnated polypropylene mesh or an injection of antibiotic were performed either simultaneously to bacterial inoculation (130, 131) or post-operatively (132). Inoculated bacteria were either
Staphylococcus epidermidis (130, 131) or Methicillin-Resistant Staphylococcus Aureus (MRSA), which was inoculated under two states: biofilm or free planktonic (132). All these studies were designed with a control group (i.e. untreated group). Mendes et al. histologically investigated the inflammatory reaction (i.e. numbers of polymorphocuclear cells, mononuclear cells, foreign body giant cells and macrophages) around inoculated (at different bacterial concentrations) and treated PU-coated implants in rats. (131) A discriminating analysis was performed to determine the factor which differentiated at best the treated groups and the non-treated groups. The authors found that this factor was the number of mononuclear cells. Thus, the use of antimicrobial agents would result in a low activation of mononuclear cells. Jacombs et al. demonstrated the protective effect of mesh against the development of capsular contracture assessed according to the Baker grading scale: the decrease of Baker III or IV capsular contracture in the mesh-treated group compared to the untreated group was highly significant. (130) Arad et al. quantified via viable bacterial count the bacterial colonization present in the specimens. (132) MRSA counts on the 11th day were significantly higher in the treated biofilm MRSA-infected group in comparison with treated free planktonic MRSA-infected group, whereas the counts were similar in the corresponding untreated groups. The authors concluded that vancomycin-based treatment would have a limited efficiency against mature biofilm. SEM demonstrated in situ biofilm from the 4th day on all the biofilm MRSA and free planktonic MRSA-inoculated implants. Moreover, although biofilm was detected on all implants and capsules, the biofilms on the antibiotic-treated implants and capsules were generally single-layered or isolated in contrast to the multi-layer biofilms found on all untreated implants and capsules. (130) Moreover, Arad et al. led a precise clinical evaluation of the rats by monitoring weight, rectal temperature and surgical wound healing. Although the wound healing scores were significantly better for untreated biofilm MRSA-infected group compared to untreated free planktonic MRSA-infected group, vancomycin significantly improved wound healing and reduced rectal temperature in free planktonic MRSA-infected group.

Recently, Atlan et al. led a histological analysis with H&E staining in rats on a large range of different breast implant surfaces. (94) The capsular surfaces in contact with Allergan smooth breast implants or Motiva breast implants were mostly flat, with an
alignment of the collagen fibres parallel to the surface. MESMO, Siltex and Microcell-textured implants elicited "small tissue projections scattered" along the surface of the capsule. The capsule surfaces facing Biocell, True Texture, Cristalline, Nagotex, Polytxt-textured and PU-coated implants exhibited "more prominent tissue projections, resulting in irregular arrangement of collagen fibres". The tissue adherence to the implant surface was also estimated by a peel test in this study. The adherence was significantly higher for the PU-coated implants than for all the other implant surfaces. Likewise, Biocell and Nagotex-textured implants adhered significantly more to the capsule than Allergan smooth breast implants or Motiva breast implants.

### 1.6.2. IN VITRO MODELS

*In vitro* models consisted of culturing cells of interest (i.e. either cells present in the surrounding host tissues or cell lines originated from breast implant-associated malignancies) or bacteria presumed to be involved in such malignancies. *In vitro* studies were performed on or without breast implant samples. Different types of *in vitro* models were published in the literature.

#### 1.6.2.1. FIBROBLAST AND MACROPHAGE-BASED MODELS

The first type characterized the biological reactions of surrounding host cells cultured on breast implant surface. The cells used were mainly fibroblasts harvested from biopsies in the breast or from skin, except for two studies which cultured Peripheral Blood Mononuclear Cells (133) or THP-1 macrophages (86). Different analyses were led, such as quantification of cell attachment, proliferation and cytotoxicity through cell viability assays. (79, 90, 92, 95) After one week, fibroblasts proliferated significantly more on smooth implant surface in comparison to textured implant surface. (92) On the contrary, Valencia et al. (90) found that fibroblast proliferation was significantly reduced on smooth surfaces. A significant increase of cell death was observed in fibroblasts cultured on textured implant surfaces. (92) The fibroblasts adhered better on the textured implant surfaces than on the smooth implant surfaces. (79, 90, 95) This adhesion result was confirmed by confocal microscopy. (79) Moreover, an immunocytochemistry observed by confocal microscopy identified a significant number of fibroblasts trapped within the valleys of the textured breast implant surfaces and a significant number of poorly spread fibroblast morphology with a random actin
network on the smooth breast implant surfaces. (90, 92) However, Barr et al. did not find any preferential attachment site for macrophages over a large range of implant surface. (86) By Fluorescence Activated Cell Sorted (FACS), Cappellano et al. demonstrated that breast implant surfaces did not induce T-cell proliferation or activation and did not alter the proportion of T-cell subsets. (133)

The gene expression of cultured fibroblasts or macrophages was quantified by real-time quantitative PCR. (86, 92, 133) A significant down-regulation of IL-8 and Tumor Growth Factor beta1 (TGF beta1) and a significant up-regulation of Heat Shock Protein60 (HSP60) by fibroblasts were observed on textured implant surfaces in comparison to smooth implant surfaces. Cappellano et al. showed an up-regulation of CD14 and IL-10 by macrophages cultured on Siltex compared to on VelvetSurface-textured surfaces. Moreover, macrophages exhibited a down-regulation of CD68 on SilkSurface and a down-regulation of TNF-alpha on SilkSurface, VelvetSurface and PU-coated implants (133) and on Siltex and Mentor smooth implants (86), whereas Barr et al. (86) found an up-regulation of TNF-alpha on Biocell-textured implants at 12h. They also noted a significant increase in IL-6 and IL-10 expression by CUI, Eurosilicone and PIP textured surface at 24h.

The cytokines released by the cultured cells were also profiled. A peak of TGFbeta1 secretion by fibroblasts on both smooth and textured implants was determined at one week. (92) POLYtxt-textured implant elicited increased production of IL6, IL1beta and TNF-alpha by the macrophages. (133) An increased level of TNF-alpha was also found with Biocell-textured and smooth implant surfaces at 12h and with Biocell, CUI and Eurosilicone textured implant surfaces at 24h. (86)

Cappellano et al. mitigated the relevancy of such models by detailing the factors which were not taken into account in these studies, such as the protein coating underwent by all surfaces once implanted in the body, the in vivo mechanical solicitations and the particulate shedding. All these factors are of prime importance in the interaction between host cells and breast implant surfaces.

### 1.6.2.2. MALIGNANT CELL LINE-BASED MODELS

The second type of *in vitro* model biologically analysed established model cell lines issued from patients with T-cell breast lymphoma (134), primary cutaneous ALCL lines and BIA-ALCL lines (47) or BIA-ALCL lines, cutaneous ALCL lines, non-anaplastic
cutaneous T-cell lymphoma lines and Jurkat lymphoblastic cell line (135). Kadin et al. (47, 135) also used BIA-ALCL cells from clinical specimens.

Lechner et al. performed a large panel of biological tests on cell lines, such as karyotype analysis and histological (H&E and Wright-Giemsa staining) examinations. (134) The malignant cells were therefore characterized by an abundant cytoplasm with one to four large cytoplasmic vacuoles and an enlarged nucleus and by an abnormal, hypertriploid and complex karyotype.

Immunohistochemistry determined similar expression of the transcription factors SOCS3, JunB and SATB1 between BIA-ALCL lines and primary cutaneous ALCL lines and detected the transcription factor GATA3 and the allergy-associated immunoglobulin IgE decorating the mast cells and dendritic cells in clinical samples of BIA-ALCL. (47, 135)

A quantitative PCR of tumor suppressor genes, proto-oncogenes and apoptosis-related genes determined a significant up-regulation of the antiapoptotic genes survivin and BCL2L2 and a significant down-regulation of proapoptotic genes and tumor suppressor genes (such as BID, BAK and BBC3) by the BIA-ALCL cell lines compared to normal donor T-cells. (134) Moreover, a PCR performed on tissue section revealed a production of IL13 (which is the signature cytokine of allergic inflammation) by the BIA-ALCL cell lines and by the BIA-ALCL cells. (135) A gene array analysis highlighted the expression of Interferon gamma (IFNgamma) and SOCS3 by the BIA-ALCL cell lines. (47)

FACS analyses were led to quantify the expression of normal T-cell lineage markers and transcription factors, with cytometric bead array to profile some cytokines in supernatants and with Annexin V/propidium iodide staining to count viable cells in the presence or absence of cell signalling inhibitors or chemotherapeutic drugs. (134) FACS was also performed after seeding and incubating BIA-ALCL cells in tissue culture medium by Kadin et al. (47) Thus, a strong activation of JAK/STAT3 signalling pathway and a strong secretion of IL-6 and IL-10 were reported on the BIA-ALCL cell lines, whereas BIA-ALCL cells exhibited a high production of IFNgamma and IL-17 (which is the signature cytokine of Th1/Th17 cells) and a nuclear JunB activity. Moreover, a STAT3 inhibition or a SHP-1 activation or chemotherapy reagents effectively killed all the BIA-ALCL cell lines. The pattern of transcription factor expression was consistent with the Th1 and T-regulatory phenotypes of lineage cells.
Functionality of the lineage cells, especially the suppressive ability of T-regulatory cells, was also evaluated. Basically, the authors co-cultured cell lines with naive normal donor T-cells and measured T-cell proliferation by carboxyfluorescein succinimidyl ester dilution. Thus, all the BIA-ALCL cell lines were found to increase T-cell proliferation.

1.6.2.3. MICROBIAL MODELS

Bacterial studies of the microbiome present on breast implant surface were the third type of in vitro models. In vitro bacterial attachment assays were carried out by Jacombs et al. (129), Jones et al. (85) and James et al. (91) to analyze the influence of implant surface on rate of bacterial growth and adhesion to implant. Jacombs et al. only used Staphylococcus epidermidis, whereas Jones et al. incubated a large range of breast implant surfaces with four bacterial types: Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa and Ralstonia pickettii. James et al. used a biofilm reactor with 3 bacterial species: Staphylococcus epidermidis, Pseudomonas aeruginosa and Ralstonia pickettii. Quantitative bacterial analysis by standard plate culture was provided at 2, 6 and 24h of incubation. Jacombs et al. counted 11-, 43- and 72-fold more bacteria on textured implants at 2, 6 and 24h respectively, compared with smooth implants. Similarly, the number of Staphylococcus epidermidis and Ralstonia pickettii at 24h and the number of Pseudomonas aeruginosa at 2h, as well as the thickness of the biofilm observed with Confocal Scanning Laser Microscope, were significantly higher on rougher breast implant surfaces (Siltex and Biocell-textured surface) compared to SilkSurface and VelvetSurface-textured surfaces. (91) Consistently, Jones et al. found a significant higher number of Staphylococcus epidermidis, Staphylococcus aureus and Ralstonia pickettii attached to PU-coated, Biocell, Nagotex, Eurosilicone or POLYtxt textured surfaces than to smooth implant surfaces. Moreover, they determined a significant linear relationship between implant surface area and growth of the four bacteria studied. However, according to Jones et al. environmental factors must be considered to study the proneness of surface to form biofilm. Moreover, James et al. mitigated the relevancy of such studies because "the immune response to the implant and associated bacteria/biofilm likely plays an important role".
### 1.6.3. EX VIVO MODELS

A third type of model consisted in harvesting and analyzing samples from the implants or from the periprosthetic tissues or fluids surrounding the implant, once retrieved from the patient. Numerous different analyses were led.

#### 1.6.3.1. HISTOLOGY

Different histological features were reported on the capsular samples, such as fibroblasts, inflammatory cells and immune cells (136). Thus, fibroblasts constituted the most common cell type in the capsule, with macrophages, scattered polymorphonuclear leukocytes, lymphocytes, plasma cells and mast cells. Myofibroblasts were also highlighted on the outer area of the capsule. Moreover, the myofibroblast layer with grade III contracture was significantly thicker than with grade IV contracture. (137) An examination of the H&E-stained tissue section under total polarized light highlighted birefringent materials (assumed to be silicone). (138, 139) 78% of the capsule adjacent to saline-filled Biocell-textured implants and analyzed by Lesesne et al. exhibited bifringent material. (138) Other studies observed extracellular silicone fragments (140), silicone-containing deposits (119), extravasated silicone or PU (141, 142) or silicone droplets (139, 143). Bifringent materials within multinucleated giant cells (138, 141), vacuolated histiocytes or macrophages (119, 140) were interpreted as an engulfment of silicone by these cells. The capsular thickness was also measured and was found to be correlated with the Baker score. (119, 136, 144) Prantl et al. even proposed a correlation between two scores of capsular contracture: the one clinically assessed (Baker grade) and the other histologically evaluated (Wilfingseder grade). (119) Moreover, a higher capsular thickness was associated with a higher number of silicone particles and silicone-loaded macrophages. The presence of synovial-like metaplasia (transformation of one differentiated cell type to another differentiated cell type) or hyperplasia (proliferation of cells) was also reported and found more frequently around textured implants. (144, 145) According to Wyatt et al., an increase of the implant duration decreased the presence of the synovial-like metaplasia around both smooth and textured implants. (145) The density and alignment of collagen fibers were extensively analyzed. Thus, collagen fibers arranged parallel to the implant surface were more often observed around smooth implants than around textured implants after 5 years. (145) Moreover, an increasing implant duration
reduced the dense collagenous architecture and the parallel orientation of collagen fibers around textured implants (145) and around smooth implants (146). The collagen fiber alignment was found even sometimes non-uniform around an implant, especially between the plane surface and the concave surface of the implants. (146) Prantl et al. summarized the histological structure of periprosthetic capsule as a 3-layer structure (119) (Fig. 6):

* The first layer constituted of macrophages, fibroblasts and in some cases synovial-like metaplasia

* The second layer characterized by a loosely arranged connective tissue and by an internal vascular supply

* The third layer contained a dense connective tissue and an external vascular supply

<figure><img src="image_8.png" /><figcaption>Figure 6: Three-layer composition of a periprosthetic capsule (Masson Goldner stain; magnification: x4). (119)</figcaption></figure>

Calcification was also reported in 25% of the capsules. The high degree of capsular contracture was associated with the presence of capsular calcification. (142)

#### 1.6.3.2. IMMUNOSTAINING

Some histological analyses of the periprosthetic capsule were completed by immunohistochemical staining of the cell immune-phenotypes. (147, 148) Thus, activated T-helper cells and macrophages were detected beneath the contact zone as well as perivascularly, whereas histiocytes represented a minor cell component. Moreover, textured implants elicited a more marked T-cell response than smooth implants, with a similar proportion of T-helper and T-cytotoxic cells.
Immunohistochemistry also revealed that TGF-beta was present in all the capsules analyzed, identified two additional recurrent rearrangements (DUSP22 and TP63 rearrangements) and confirmed that the JAK-STAT3 signaling pathway was activated in all the cases tested. (42, 149) Recently, Walker et al. co-localized the fluorescent pattern obtained by immunostaining of host proteins (such as collagen and fibrinogen) with a bacterial fluorescent pattern in order to image the potential bacterial binding ligands on the implant surface. (117) Staphylococcus epidermidis predominantly co-localized with collagen, while group B streptococci and Klebsiella pneumoniae co-localized with fibrinogen.

### 1.6.3.3. CHEMICAL AND SURFACE ANALYSES

Chemical and surface analyses were performed on biological and prosthetic specimens. Rudolph et al. used Transmission Electron Microscope (TEM) and SEM to detect silicon around breast implant via energy dispersive X-ray analysis. (150) Silicone and other foreign materials (such as PU and Dacron) were also identified in surrounding tissues with a Raman microprobe. (151) A quantitative measurement of silicone in breast tissue was performed with an atomic absorption spectroscopy. (139) Thus, silicon was identified in half the tissue specimens (and only around gel-filled implants) by X-ray analysis and in all the capsules surrounding gel-filled implants by Raman microprobe. Likewise, PU and Dacron were detected in all the capsular tissues enveloping PU-coated and Dacron-patched gel-filled implants respectively. Moreover, on the 49 breasts with unruptured prostheses analyzed by Thomsen et al. (139), a positive relation between the concentration of silicone in the capsular tissue and the inflammatory reactions was determined, contrary to Siggelkow et al. (144). Del Rosario et al. observed in tissue sections the ultrastructure of cells with TEM and performed Electron Probe X-ray microanalytic studies to determine a more precise location of silicon in the capsular tissue. (152) Thus, high concentration of silicon was detected within phagocytic cells and in the collagen stroma of the breast implant capsules. Interestingly, all the cases featuring synovial-like metaplasia demonstrated abundant silicone particle deposition.

Legrand et al. led complementary X-ray and Nuclear Magnetic Resonance (NMR) investigations on calcifications observed in the vicinity of old breast implants (especially on those manufactured prior to the mid-eighties) removed for detected
ruptures and/or grade IV capsular contracture. (153) Micro-analyses confirmed the presence of calcium and silicon for all samples and a bone-like hydroxyapatite structure. These large crystals were detected either in contact with breast implant or in deeper collagen layers of the capsule.

Amoresano et al. performed chemical analyses on the gel extracted from explanted breast implants via Fourier Transform infrared spectroscopy (FTIR) and gas-chromatography mass spectrometry (GC-MS). (154) Thus, these analyses revealed the presence of organic substances (such as fatty acid) in very low concentration in all the samples and therefore the possibility of bioaccumulation and tissue contamination of the gel.

Some authors visualized the surface of the capsule in contact with the implant by SEM. (88, 89, 152, 153, 155) Danino et al. was one of the first suggesting on the basis of microscopic images of the capsule that the capsules enveloping Biocell or CUI textured implants "present a mirror image with correspondence of the depressions on the prosthesis and contacts on the capsule". (89) This effect – called “Velcro effect” – was not present with Arion or Sebbin textured implants. (Fig. 7) From these examinations, Danino et al. proposed the hypothesis of a critical size of the pores, which would elicit tissue ingrowth inside the pores and therefore the “Velcro effect”. Consistently, this capsular characteristic was also found along the surface of the inner capsule in the case of double-capsules around Biocell-textured implants.
<figure><img src="image_9.png" /><figcaption>Figure 7 : « Velcro effect ». A : implant surface (Biocell). B : capsule surface. (SEM ; magnification : x50)(88)</figcaption></figure>

1.6.3.4. MICROBIOLOGICAL ANALYSES

Microbiological analysis was firstly performed in order to establish a correlation
between the degree of capsular contracture and bacterial presence on explanted
breast implant surface (156-158) and in capsular tissue (142, 159). "Routine" culture
methods were used, as well as special culture technique designed to recover bacteria
adhering and encased in biofilm. Basically, this technique consisted in prolonged
incubation with continuous agitation and in some cases with maceration/sonication
(159) or vortexing/sonication (160). Then, both removed breast implant surface and
capsular tissue were cultured. Thus, bacteria were significantly more detected on
samples obtained from patients with contracted capsules than from patients with non-
contracted capsules (156-161), contrary to the conclusions of Poppler et al. (162). The
predominant isolate was Coagulase Negative species, mainly the Staphylococcus
epidermidis group. (156, 157, 159) Pajkos et al. also determined that the presence of
Coagulase Negative species was significantly associated with capsular contracture.
(159) Other microorganisms were also isolated, such as Propionibacterium species
(158, 160, 161), Corynebacterium species (160), Staphylococcus aureus and Escherichia coli (161).

Bacterial culture may be coupled with real-time quantitative PCR technique (117), in order to quantify the total number of bacteria in the periprosthetic capsule via the 16S rRNA gene (64) and to identify bacterial species on breast implants and tissues via Next-Generation Sequencing (NGS) technique and more particularly pyrosequencing of the 16S rRNA gene (64, 117). Walker et al. confirmed that the predominant bacteria identified on samples from patients with capsular contracture was Staphylococcus epidermidis. (117) Moreover, Hu et al. demonstrated a different microbiome between BIA-ALCL samples and high-grade contracted capsule samples. (64) Thus, there was a significantly greater proportion of Ralstonia pickettii present in BIA-ALCL and contralateral breast specimens compared with high-grade contracted capsule specimens. Conversely, significantly more Staphylococcus epidermidis were found associated with high-grade contracted capsule specimens. However, they observed a similar total number of bacteria on BIA-ALCL samples and on high-grade contracted capsule samples (approximately 4.7-4.9 10⁶ cells/mg tissue). Regarding benign cases, Walker et al. identified a different microbiome on clinically normal breast implants (colonized by only Gram-positive bacteria and specifically Coagulase Negative Species) and on clinically normal tissue expanders (colonized by a broader array of Gram-positive and Gram-negative bacteria).

Alternatively, SEM was used to image bacteria and biofilm on capsular and prosthetic biopsies. (Fig. 8) (64, 156, 159) The presence of bacteria was therefore confirmed by SEM on implants. (156) Biofilm was observed on the samples from patients with capsular contracture (64, 159) and without capsular contracture (159) and on the BIA-ALCL samples (64).
<figure><img src="image_10.png" /><figcaption>Figure 8 : Biofilm imaged in capsule specimens (SEM images; magnification: x5000) (64)</figcaption></figure>

Moreover, biofilm was quantified by using the semi-quantitative scale of Van Heerden.
(155) This technique consists in grading the area of biofilm coverage present on breast
implant samples through SEM examination with a constant magnification.

1.6.3.5. PROTEIN EXPRESSION ANALYSES

Protein expression was quantified either directly or through retro-transcriptomic
analysis. Thus, protein expression contained in biological samples, such as capsular
tissue (163) and periprosthetic effusion, blood serum and blood plasma from patients
with BIA-ALCL (164), was directly quantified by ELISA. More precisely, Wolfram et al.
(2012) profiled the cytokines present in the supernatant of cultured intracapsular T-cells
and determined an expression pattern consistent with a T-helper 1 or T-helper 17
immunophenotype. Hanson et al. demonstrated a positive detection of soluble CD30
in all BIA-ALCL effusion specimens, whereas the detection was negative or weak in
BIA-ALCL serum specimens or in BIA-ALCL plasma specimens. (164)
Additionally, retro-transcriptomic studies were led by Kyle et al. (165) and Ulrich et al. (166) on both contracted and non-contracted capsular tissues. Before the qPCR assay, Kyle et al. performed a whole genome array analysis in order to discriminate the most dysregulated genes in contracted capsules, compared to normal capsules. Thus, the genes aggrecan, TIMP4 (Tissue Inhibitor of Metalloproteinase) and TNFSF11 (Tumor Necrosis Factor ligand Superfamily member) were significantly down-regulated in contracted capsules. Conversely, the genes MMP12 (Matrix Metalloproteinase), SAA1 (Serum Amyloid A) and IL8 were significantly up-regulated. These genes are either involved in the structure or in the degradation and the remodeling of the Extra-Cellular Matrix (ECM) (such as the genes aggrecan, TIMP4 and MMP12), or in the inflammatory reaction or in the recruitment of inflammatory or immune cells (such as the genes TNSF11 and SAA1). Ulrich et al. studied more precisely the expression of a panel of genes mediating the remodeling of the ECM, according to the type of breast implant surface. The expression of MMP2 was significantly up-regulated in capsular tissues from patients with grade II/III/IV capsular contracture in comparison to grade I. This significant up-regulation was only observed with textured implants. Conversely, the up-regulation of TIMP1 and TIMP2 was significant with both smooth and textured breast implants. Then, the authors computed the MMP/TIMP ratio and concluded that the ratio was significantly lower in tissue from patients with a high degree of capsular contracture in comparison to those with grade I, whatever the type of breast implant surface. (163)

#### 1.6.3.6. MOLECULAR BIOLOGY

NGS techniques, such as Whole Exome Sequencing (WES), were applied to screen the genetic mutations present in the effusion fluid and bone marrow (48) and in the capsules (42) of patients with BIA-ALCL. Thus, three genetic aberrancies resulting in the activation of the JAK/STAT3 pathway were reported.

Fluorescent In-Situ Hybridization (FISH) technique was also performed to confirm the presence of Ralstonia pickettii on BIA-ALCL samples.

#### 1.6.3.7. BIOMECHANICAL ANALYSES

Biomechanical analyses were performed on capsular samples. The contractile ability of dissected capsule specimens was demonstrated by exposure with smooth-muscle
stimulants and relaxants. (167) Quantitatively, capsular tissues from 69% of the patients responded to smooth-muscle relaxants and 75% responded to smooth-muscle stimulants. Then, Hwang *et al*. measured the capsule tensile strength in a saline solution and determined that the tensile strength of the capsule was correlated positively with the degree of capsular contracture. (137) Moreover, the tensile strength in the myofibroblast negative group was significantly higher than in the positive group. More recently, on the basis of mechanical tests Ben Amar *et al*. implemented two mechanical models of the capsular tissue according to the Baker grading. (168) Thus, Baker grade I samples were modeled as an anisotropic material with well-oriented fibers, whereas the orientation effect was lost for Baker grade III samples.

1.6.3.8. MECHANICAL, CHEMICAL AND SURFACE ANALYSES ON RETRIEVED IMPLANTS

Several studies were led to assess the in-situ ageing of breast implants. Amoresano et
al. (2016) performed similar mechanical tests as previously on implanted and non-
implanted prostheses and reported a greater deformation on explanted outer shell
samples than on the virgin materials, suggesting an in vivo mechanical weakening of
the outer shell. (154) Bodin et al. led the analyses according to the ISO 14607 standard
and determined that the breaking strength, the breaking stress and the elongation at
break decreased with the implantation duration. (169) Tortolano et al. performed
chemical analyses by GC-MS on saline-filled expanders, which allowed to study the
release and the penetration of chemical substances of the shell without the impact of
the silicone gel. (170) Thus, the authors detected cholesterol and fatty acids on all the
shells and identified siloxanes in the saline solution. These chemical changes could
explain the mechanical ageing of the shell. The first article, which suggested wear of
the breast implant shell and therefore a release of silicone particle from the shell, was
Danino et al. (88) They reported micrometric silicone particles released from Biocell-
textured implant and embedded in the capsular tissue. A simulation was published by
Ramiao et al., who led an in vitro degradation process in a buffer solution at pH 7.4
and pH 4.0 and at a controlled temperature of 37°C according to the ISO 10993
standard (Biological Evaluation of Medical Devices). (171) Thus, they observed by SEM
no morphological alteration of the textured breast implant surface over a period of 12
weeks.
# CHAPTER II: MEASUREMENT INSTRUMENT AND MULTI-SCALE ANALYSIS

According to the manufacturers, the breast implant outer shells feature very different and characteristic states of surface. Some surfaces exhibit "pores" or "peaks" or "fibrils". (see section 1.3.4) Before discussing the biological and clinical impact of these states of surface, a thorough characterization of these topographies is of prime importance. Firstly, an appropriate and validated methodology of measurement must be chosen. Thus, numerous instruments, such as SEM, laser confocal microscope or X-ray Micro-tomography, were used in the literature to measure breast implant surfaces. Moreover, the sampling and the sample size of these studies were inconsistent, which provided discrepant results. (see section 1.3.3) In order to have a robust characterization of surface and to be able to extrapolate and compare outcomes from other studies, a unique methodology (in term of instrument, sampling, sample size and cleaning) must be commonly adopted. In order to be validated, the methodology must be based on comparative studies of several instruments. Before our article published in June 2017 (which is presented below), no multi-instrument analysis was led to validate the choice of instruments. Moreover, as the biological mechanisms of interest involves several entities which have a very wide range of dimension, the analysis must be also led on a representative range of scale. This approach was considered by Barr et al. (97), who captured by SEM different surface areas of a same sample.

Recently, a new update of the standard relative to breast implant (ISO 14607: 2018) was released in May 2018 and proposes in an informative Annex a more complete methodology of measurement than previously. Thus, the standard requires for every type of surface (smooth or textured) a sampling of 15 measurements over 4mm² repeated on three different implants and propose four different instruments: SEM with a 2D or 3D reconstruction software, Laser confocal microscope, Interferometer or AFM. SEM with a 3D reconstruction software and more generally the methodology of the standard was grossly applied in the report mandated by the ANSM.

(https://ansm.sante.fr/S-informer/Points-d-information-Points-d-information/Surveillance-des-implants-mammaires-par-l-ANSM-publication-d-un-avis-)
[d-experts-de-CSST-et-d-une-etude-sur-la-texturation-Point-d-information](#) However, they restricted their analysis to only 9 measurements per implant and only measured 2.5mm² for implants featuring no or a slight texture.

The purpose of this chapter is to discuss the choice of measurement instrument according to the type of surface (such as “smooth”, “microtextured” or “macrotextured” surface). A multi-scale analysis was then designed to compare the instruments over a characteristic range of scales.

## 2.1. MULTI-SCALE ANALYSIS

A such comparison between Interferometer, Focus variation microscope and X-ray Micro-tomography was published between the different surfaces of Sebbin breast implant (Sebbin shaped textured implant, Sebbin round textured implant, Sebbin round microtextured implant and Sebbin round smooth implant), which is one of the most comprehensive portfolio of surface among manufacturers. (article below) The sampling specified in the ISO 14607: 2009 (i.e. 9 measurements over 4mm² on a single implant), which was in force at the time of the publication, was applied. The multi-scale analysis was led on the five metrological parameters stipulated in the ISO 14607:2018 (i.e. Sa, Sq, Sz, Sku, Ssk). The measurement principles and the settings of apparatus as well as the multi-scale decomposition of topographies were also explicated in the article. In fine, this comparison shed light on some limitations of Micro-tomography and Focus variation microscope, compared to Interferometry.