Preoperative diagnosis of BRCA1/2 mutation impacts decision-making for risk-reducing mastectomy in breast cancer patients.

Decision to undergo risk-reducing mastectomy (RRM) needs to consider several factors, including patient's preference, surgeon's preference, family history, and genetic predisposition. The aim of this study was to examine whether preoperative diagnosis of BRCA1/2 mutation status could influence surgical decision-making in newly diagnosed breast cancer patients. We retrospectively reviewed ipsilateral breast cancer patients with BRCA1/2 mutation who underwent primary surgery between January 2008 and November 2019 at a single institution in Korea. Of 344 eligible patients, 140 (40.7%) patients were aware of their mutation status 'prior to surgery', while 204 (59.3%) did not. Contralateral RRM rate was significantly higher in the group with BRCA1/2 mutation status identified 'prior to surgery' compared to the group with mutation status identified 'after surgery' [45.0% (63/140) vs. 2.0% (4/204)] (p < 0.001). Reduced turnaround time of BRCA1/2 testing (p < 0.001) and the use of neoadjuvant chemotherapy (p < 0.001) were associated with BRCA1/2 mutation status identified prior to surgery. Although not statistically significant, higher incidence of developing contralateral breast cancer for BRCA1/2 mutation carriers who underwent ipsilateral surgery-only compared to those who underwent contralateral RRM was observed [12.1% (95% CI: 7.7-17.7%)] (p = 0.1618). Preoperative diagnosis of BRCA1/2 mutation could impact surgical decision-making for breast cancer patients to undergo risk-reducing surgery at the time of initial surgery.