BRCA1 and breast cancer: In all, 19 contralateral breast cancers occurred in follow-up (Table 5): 1 in a TP53 carrier, 4 in BRCA1 carriers and 1 in BRCA2. In the enriched mutation carrier data set, there is a 2% annual risk of contralateral breast cancer up until 15 years, after which the number of patients is too small for any stable estimate (Figure 2B).