BRCA1 and Familial prostate cancer: BRCA2 is estimated to be present in about 1-2% of sporadic prostate cancer cases, leading to an 8.6-fold increase in the risk of prostate cancer, while BRCA1 increases the risk of sporadic prostate cancer by 3.5-fold, but it is present in only 0.44% of prostate cancer cases (2, 3).