Locoregional Treatments and Ipsilateral Breast Cancer Recurrence Rates in BRCA1/2 Mutation Carriers

Purpose: There is a paucity of data on the rates of ipsilateral breast tumor recurrence (IBTR) in BRCA1/2–associated breast cancer (BC). Scarcer yet are outcomes data in BRCA1/2 mutation carriers in the setting of newer mastectomy techniques, such as skin-sparing mastectomies (SSM) and nipple-sparing mastectomies (NSM). Methods: Data were extracted from the medical records of BRCA1/2 carriers who were diagnosed with BC and treated at a single institution between 2006 and 2020. The data extracted included patient demographics, tumor characteristics, disease stage, surgical treatment, use of radiation therapy (RT), and disease outcome. Results: Overall, 255 BC patients with BRCA1/2 germline mutations were identified. Of these, 128 (50.2%) underwent a mastectomy (SSM or NSM in 82% of them), 76 (59.4%) without postmastectomy RT (non-PMRT) and 52 (40.6%) with PMRT, whereas 127 (49.8%) elected for breast-conserving treatment (BCT). The non-PMRT group had earlier disease stages (82.3% were Tis and T1N0) compared with the PMRT and BCT groups (3.6% and 48.1%, respectively; P < .05). The IBTR cumulative rate was 9 of 76 (11.8%) in the non-PMRT cohort compared with 0 of 52 in the PMRT group (P = .01) and 6 of 127 (4.7%) in the BCT group (P = .06). The cumulative incidences of IBTR at 5 and 10 years were 9.8% and 27.4%, respectively, in the non-PMRT group versus 2% and 11.3%, respectively, in the BCT group (P = .0183). No significant difference in overall survival was observed at the time of follow-up. Conclusions: BRCA1/2 mutation carriers treated with mastectomy without PMRT had higher rates of IBTR than those who underwent mastectomy and PMRT or BCT, despite earlier stages of disease. The safety of SSM/NSM should be evaluated in a prospective trial.