Are BRCA1 mutations a predictive factor for anthracycline-based neoadjuvant chemotherapy response in triple-negative breast cancers?

Abstract

580 Background: BRCA1 being involved in DNA repair and apoptosis, its mutations may influence response to chemotherapy. In vitro studies demonstrated that loss of BRCA1 function increased sensitivity to platinum compounds and induced resistance to anthracyclines. BRCA1-related breast cancers tend to be ductal carcinomas with high tumor grade, absence of hormonal receptors and no HER2 overexpression, so called triple-negative. We retrospectively analyzed anthracycline-based neoadjuvant chemotherapy efficacy in triple- negative tumors according to BRCA1 status. Methods: 393 breast cancer pts were treated with FEC100 neoadjuvant chemotherapy (FU 500 mg/m2, epirubicine 100 mg/m2, cyclophosphamide 500 mg/m2) between 1/2000 and 12/2006. Out of them, 14% had a triple-negative phenotype (55 pts). Patients with young age at diagnosis or family history of breast cancer were offered genetic testing for BRCA1 and BRCA2 mutations. Twelve of these patients had a BRCA1 deleterious mutation with a triple-negative tumor. Characteristics of these 12 pts at diagnosis were: median age = 38, tumor stage = 7 T2N0, 2 T2N1, 2 T3N0, 1 T3N1. Results: Pathological complete response was defined as absence of invasive tumor in breast and axillary nodes. After 6 cycles of FEC100, 42% of patients with triple-negative tumors (23/55) had a pathological complete response, compared to 17% (2/12) with a BRCA1 mutation. Only one of the 12 BRCA1 patients had an axillary node involvement. Conclusions: In our series, BRCA1 deleterious mutations decreased anthracycline-based chemotherapy efficacy in triple- negative breast cancers. Platinum compounds should be evaluated in these BRCA1-related tumors. No significant financial relationships to disclose.