BRCA1 and breast cancer: The following attributable risk percentages for such factors have been reported in the literature: 10.7% due to high alcohol intake, 15.0% due to low beta-carotene intake, 8.6% due to low vitamin E intake, 11.6% due to low levels of physical activity [11], 5.0% due to BRCA1 and BRCA2 mutations [12], 29.5% due to late age at first birth and nulliparity, 9.1% due to family history of breast cancer [13], and 2.5% due to smoking [14].