Multinational retrospective cohort study of surgical management of early-onset breast cancer among young BRCA1/2 carriers

Young BRCA1/2 carriers may undergo breast-conserving surgery (BCS) or mastectomy with or without contralateral risk-reducing mastectomy at the time of an index breast cancer diagnosis. A variety of factors may influence surgical decision-making. The retrospective BRCA BCY cohort study, at 109 centers across 5 continents, explored surgical patterns of care and factors associated with uptake of bilateral mastectomy among BRCA1/2 carriers diagnosed with early-onset breast cancer before age 41 years between 2000 and 2020. Among 5660 eligible BRCA1/2 carriers, 4715 women (median age 35 years; IQR 31-38) had stage I-III breast cancer with surgical details available. In this cohort, 1805 patients (38.3%) underwent BCS, 1752 (37.2%) underwent unilateral mastectomy, and 1158 (24.6%) underwent bilateral mastectomy. The figure shows that uptake of BCS decreased over the study period, whereas the use of bilateral mastectomy increased. Bilateral mastectomy was more common in women who had genetic testing performed before or within 6 months of a breast cancer diagnosis compared with those tested after diagnosis. On multivariable analysis, compared with those tested after diagnosis, earlier genetic testing was the factor most strongly associated with bilateral mastectomy receipt. In adjusted analyses, geographic region and genetic testing performed at or before diagnosis were associated with bilateral mastectomy receipt. The authors conclude that the findings of this study support early genetic testing for young women with breast cancer to help optimize local therapy decisions.