Can contralateral prophylactic mastectomy and oophorectomy increase survival in BRCA-related breast cancer? Results from the Italian MUTina study.

Introduction: In the Emilia-Romagna region of Italy, a unique Hub and Spoke model was adopted to recognize BRCA-related breast cancer (BC) patients. Characteristics and outcomes of tumors identified by this model will be presented.

Methods: This multicenter retrospective cohort study involved patients diagnosed with BRCA-related BC identified in the Emilia-Romagna region between January 2000 and December 2013. Seven provinces collected data on patient and tumor characteristics; clinical and gene testing information were also registered. Comparisons between BRCA1 and BRCA2 BC were performed. To balance different variants to identify significant predictors of survival, an inverse probability of treatment weighting (IPTW) analysis on Cox regression was conducted.

Results: From 2000 to 2013, 284 BRCA-related BC were registered (171 BRCA1, 110 BRCA2, and 3 BRCA1 and BRCA2). BRCA1 were diagnosed at an earlier stage compared to BRCA2 (50.1 % vs 30 %, respectively, in stage I, P = 0.0015). BRCA2 patients underwent more up-front surgery (85 % vs. 74.9 %, P = 0.049) and less chemotherapy (69.1 % vs 88.9 %, P = 0.004) than BRCA1 patients. At 11.8 years median follow-up, BRCA1 patients developed more second contralateral BC (P = 0.09), while BRCA2 had more visceral relapses (P = 0.013). No differences in overall survival (OS) between BRCA1 and BRCA2 patients (P = 0.07) were found. An advantage in OS was independently seen for patients who underwent contralateral prophylactic mastectomy (P = 0.0001) and oophorectomy (P < 0.0001).

Conclusions: In conclusion, adopting a homogeneous regional framework provides important information about prevention and treatment strategies of BRCA-related BC and suggests using maximal surgery to improve OS.