Su L, Xu Y, Ouyang T, et al. - Researchers examined BRCA1/2 carriers in a large cohort of unselected Chinese breast cancer patients for estimating their cumulative risk of contralateral breast cancer (CBC). They determined BRCA1/2 germline mutations in 9,401 unselected Chinese breast cancer patients. In this cohort, CBC developed in 181 patients after a median follow-up of 5.7 years. Relative to non-carriers, the risk for CBC was 4.52-fold and 5.54-fold higher in BRCA1 and BRCA2 carriers, respectively. This suggests that in unselected Chinese breast cancer patients, BRCA1/2 carriers are at substantial higher risk of CBC. They identified much more remarkable CBC risk in both BRCA1 and BRCA2 carriers who had a family history of breast cancer. Younger age at first breast cancer diagnosis also intensified CBC risk in BRCA1 carriers.