Prostate cancer develops in the epithelial cells of the glandular elements of the prostate. 95% of prostate cancers are adenocarcinomas. There is no single cause of prostate cancer. 9% of prostate cancers are caused by a genetic susceptibility, probably inherited via a gene on chromosome 1. Proven risk factors for prostate cancer include old age and positive family history. Probable risk factors include a high intake of dietary fat and high levels of serum testosterone.