Breast-conserving surgery in BRCA1/2 mutation carriers

Abstract

Ten percent of women with breast cancer who are treated with breast-conserving surgery (BCS) are known to have a risk of developing an ipsilateral-breast tumor recurrence (IBTR). It has been suggested that BRCA mutation carriers have a higher rate of local recurrence although findings are still inconsistent between studies. Hence, the optimal local therapy for women with BRCA-associated breast carcinoma remains controversial. We report the outcome of BCS in BRCA mutation carriers in a Chinese cohort. Between 1979 and 2013, a total of 786 women were recruited for genetic testing based on clinical risk through the Hong Kong Hereditary Breast Cancer Family Registry. 62 women were found to be BRCA1/2 mutation carriers of whom 9 had ovarian cancers. 241 [30.7% (241/786)] women had BCS performed. This included 21 [8.7% (21/241)] carriers with 1 having bilateral BCS and these were compared with 144 [59.8% (144/241)] non-carriers of whom 2 had bilateral BCS. Primary end points were incidence of IBTR/local regional, contralateral breast cancer if first presentation was ipsilateral breast cancer, and distant relapse. Median follow up was 71 and 57 months for the two groups respectively. Median age was 46 and 45 for carriers and non-carriers. Overall local relapse rate was not significantly different from BCS to mastectomy cases in the whole cohort who had genetic testing [8.3% (38/546) vs 7.0% (20/241), P = 0.554]. For those who had BCS, local recurrence rate was 4.8% (1/21) in carriers and 11.1% (16/144) in non-carriers. There was no significant difference (P = 0.446) in the tumor size being 1.80 cm vs 1.61 cm respectively. Five-year cumulative incidence of IBTR was 2.3% for mutation carriers and 2.7% for non-carriers [hazard ratio = 1.217; 95% confidence interval (0.274, 5.410); P = 0.797]. Five year cumulative incidence of distant relapse after BCS for BRCA mutation carriers was not statistically higher than non-carriers (5.9% vs 9.4%, p = 0.452). Our data suggest that local relapse risk after BCS is not statistically higher than that of mastectomy in BRCA mutation carriers, but higher risk for non-carriers. However being a carrier does not increase the risk of IBTR after BCS. These risks of developing local relapse should be discussed with carriers when deciding on the option of breast conservation surgery and also risk-reducing strategies.