BRCA1 and breast cancer: In premenopausal women with a recent diagnosis or history of BC and BRCA1/2m, several large studies have demonstrated that oophorectomy confers strong reductions in risk of subsequent BC, as well as mortality.100–106 Metcalfe et al.105 studied the benefits of oophorectomy soon after a diagnosis of BC in BRCA1/2m carriers (mean age at diagnosis ~42 years).