Familial prostate cancer is a cluster of prostate cancer within a family. Most cases of prostate cancer occur sporadically in people with no family history of the condition. However, approximately 5% to 10% of prostate cancer cases are believed to be primarily caused by a genetic predisposition to the condition. In many families, the underlying genetic cause is unknown; however, some of these cases are caused by changes (mutations) in the BRCA1, BRCA2, HOXB13, or several other genes. Other cases are likely due to a combination of gene(s) and other shared factors such as environment and lifestyle. High-risk cancer screening at an earlier age is typically recommended in men who have an increased risk for prostate cancer based on personal and/or family histories.