Hypofractionated Radiotherapy in Breast Cancer Patients With Prosthetic Reconstruction

RATIONALE:

Radiotherapy (RT) can be indicated to patients submitted to breast-conserving surgery, but, despite the benefits, adjuvant RT can cause contracture generated by tissue fibrosis in patients with immediate prosthetic reconstruction, which could cause prosthesis loss. The biological explanation of this outcome is not fully understood, but recent advances in the analysis of patient-derived blood can contribute to establishing a connection of molecular alterations related to this clinical outcome.

There is not a consensus about using hypofractionated RT schemes for patients with BCS and breast reconstruction since no studies had investigated the reasons why some patients lose the prosthesis.

PURPOSE: This study will evaluate G3 toxicity rate in breast cancer patients with immediate prosthetic reconstruction, submitted to hypofractionated radiotherapy, analyzing capsular contracture, leakage, infection, and bad positioning in order to demonstrate the noninferiority of Hypo-RT with the conventional RT. Additionally, the molecular profile of blood samples will be investigated in order to find biomarkers related to inflammations processes and response to treatment.

General aim: To evaluated if hypofractionated accelerated radiotherapy in patients with breast cancer undergoing immediate breast implant reconstruction surgery is non inferior to conventional radiotherapy.

Aim 1 (Primary objective): Assess the G3 toxicity rate - loss of the prosthesis (complication that requires surgical intervention: capsular contracture, leakage, infection, malpositioning).

Aim 2 (Specific secondary objectives):

* Compare local recurrence rate between two groups;
* Compare quality of life index between two groups using EORTC QLQ-C30 / EORTC QLQ-BR45 scales during treatment, after 6 and 12 months after treatment ending;
* Compare self-image differences between groups;
* Compare acute and late radiodermatitis rates by CTCAE 4.0;
* Analyse dosimetric planning differences considering the volumes of all breast and breast without prosthesis;
* Study inflammation molecular markers, which may indicate an increased risk of fibrosis;
* Evaluate the change in the profile of extracellular vesicles in patients treated with RT hypofractionated and conventional;
* Evaluate the change in EV collagen production after in vitro irradiation, using co-culture experiments with breast cells and fibroblasts.

Eligibility Criteria:
Inclusion Criteria:

* Women with confirmed histological diagnosis of invasive ductal carcinoma and lobular breast carcinoma;
* Radical mastectomy with immediate reconstruction with a prosthesis;
* Patients indicated for adjuvant RT;
* Any lymph node status;
* With or without adjuvant chemotherapy;
* ECOG performance status from 0-2;
* \> 18 years old;
* Informed Consent Form applied before any study-specific procedure.

Exclusion Criteria:

* Another histological diagnosis than invasive ductal carcinoma or lobular carcinoma;
* Previous history of neoplasm and/or radiotherapy and/ or quimiotherapy before this study;
* Distant metastatic disease;
* Palliative treatment;
* Patients with scleroderma / systemic lupus erythematosus.