Improved overall survival after contralateral risk-reducing mastectomy in brca1/2 mutation carriers with a history of unilateral breast cancer: A prospective analysis

Data on survival of BRCA1/2-associated primary breast cancer (PBC) patients who opt for subsequent contralateral risk-reducing mastectomy (CRRM) are scarce and inconsistent. We examined the efficacy of CRRM on overall survival in mutation carriers with a history of PBC. From a Dutch multicentre cohort, we selected 583 BRCA-associated PBC patients, being diagnosed between 1980 and 2011. Over time, 242 patients (42%) underwent CRRM and 341 patients (58%) remained under surveillance. Survival analyses were performed using Cox models, with CRRM as a time-dependent covariate. The median follow-up after PBC diagnosis was 11.4 years. In the CRRM group, four patients developed contralateral breast cancer (2%), against 64 patients (19%) in the surveillance group (p<0.001). The mortality was lower in the CRRM group than in the surveillance group (9.6 and 21.6 per 1000 person-years of observation, respectively; adjusted hazard ratio 0.49, 95% confidence interval 0.29-0.82). Survival benefit was especially seen in young PBC patients (<40 years), in patients having a PBC with differentiation grade 1/2 and/or no triple-negative phenotype, and in patients not treated with adjuvant chemotherapy. We conclude that CRRM is associated with improved overall survival in BRCA1/2 mutation carriers with a history of PBC. Further research is warranted to develop a model based on age at diagnosis and tumour and treatment characteristics that can predict survival benefit for specific subgroups of patients, aiming at further personalized counselling and improved decision making. What's new? When diagnosed with breast cancer, women naturally worry about tumors forming in the other breast as well. Sometimes, they elect to have both breasts removed, even though cancer has been detected only in one. But does the procedure have any protective effect? For certain groups, yes. In this paper, the authors collected data on the survival of several hundred patients with BRCA1/2-associated breast cancer. Removing the non-affected breast did improve survival in BRCA1/2 carriers with a history of primary breast cancer, particularly those under age 40. These findings will help doctors provide more personalized counselling and guidance regarding these decisions.