Since the discovery of the BRCA genes about two decades ago, a number of studies have reported on factors that may modify cancer risks in those who carry gene mutations. Recently, results of previously published studies were collected through a comprehensive literature review to estimate the overall effects of various risk modifiers in BRCA carriers. Results suggested that giving birth for the first time at an earlier age was likely protective against breast cancer risk. Regarding ovarian cancer, breast feeding and tubal ligation reduced risks in BRCA1 carriers, and use of oral contraceptives reduced risks in both BRCA1 and BRCA2 carriers. Interestingly, smoking raised the risk of breast cancer in only BRCA2 mutation carriers. These findings suggest that sufficient information exists on some risk factors, which may be useful when counseling patients about cancer risks or lifestyle factors to modify risks in BRCA carriers.
Friebel TM, et al. J Natl Cancer Inst. 2014 Jun;106(6). PMID: 24824314.