P4-18-02: Sentinel Node Biopsy in Extensive Ductal Carcinoma In Situ (DCIS) Diagnosed by Vacuum-Assisted Macrobiopsy (VAMB) and Treated by Mastectomy: Results of the French Prospective Trial CINNAMOME.
Authors: Tunon-de-lara C , Giard S , Baron M , Le-Bouedec G , Garbay J-R , Blanchot J , Mollard J , Charitansky H , Martin-Françoise S , Michy T , Fondrinier E , Butarelli M , Loustalot C , Raout I , Macgrogan G 
Published: June 2012

Background: Lymph node evaluation in the management of DCIS has been completely abandoned as a result of the documented low incidence of nodal metastases (&lt;2%) and the significant morbidity of lymph node dissection. However, the risk of occult invasive disease exists when the initial diagnosis is performed by vacuum-assisted micro biopsy (VAMB). Invasive disease is usually discovered during the histological analyses following mastectomy. After mastectomy, the only option for patients is complete axillary lymph node dissection (ALND). The aim of this study was to evaluate the number of ALND that can be avoided by using the sentinel lymph node (SLN) procedure to identify patients with invasive disease but no SLN involvement.

Trial design: Patients with extensive microcalcifications on mammography and DCIS diagnosed by VAMB treated by mastectomy were included in the study. The SLN procedure was performed and intraoperative evaluation on frozen sections was carried out. If the SLN was positive an ALND was performed during the same intervention. If the SLN procedure failed or was negative an ALND was not performed. Radiography of the mastectomy specimen was performed to assist the pathologist in confirming the DCIS diagnosis, to evaluate the size and to determine concordance rates between initial VAMB diagnosis and histological analyses. Results: Fourteen French cancer centers took part in this protocol over 2 years (May 2008-December 2010). 228 patients were enrolled, including 197 DCIS on VAMB. The SLN was identified in 193 cases (98%) but one case was not documented at histology leaving 192 valid cases for analysis.

Distribution of SLN results and histological lesions found on mastectomy specimens in the series

ALND was not performed for non-invasive disease and negative SLN (n=114) and invasive or micro-invasive disease and negative SLN (n=51). This meant that ALND was avoided for 67.1% of the patients with invasive disease (51/76, 95%CI[56.5−77.7]), or 26.6% of patients overall (95%CI [20.3−32.8]), whereas these patients would have previously received ALND without the use of the SLN procedure. We observed 39.6% (76/192) of discordance between VAMB results and definitive results from histology analysis after mastectomy across all patients.

Conclusions: SLN is a useful procedure for patients with DCIS diagnosed by VAMB treated by mastectomy and presenting extensive microcalcifications on mammography. For patients for whom microinvasive or invasive carcinoma is later identified on the mastectomy specimen, the use of this procedure makes it possible to spare over a quarter of them from ALND and the associated morbidity. Biological analyses are currently underway to determine predictive factors of invasive disease associated with DCIS.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-18-02.