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

Abstract

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). 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. 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. 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.