Prostate cancer is a disease in which cancer develops in the prostate. These cells may spread (metastasize) from the prostate to other parts of the body, especially the bones and lymph nodes. Prostate cancer may cause pain, difficulty in urinating, erectile dysfunction and other symptoms. Prostate cancer develops most frequently in men over fifty. This cancer can only occur in men; the prostate is exclusively of the male reproductive tract. Prostate cancer is most often discovered by physical examination or by checking the blood for PSA (prostate specific antigen). Diagnosis is made by obtaining a prostatic biopsy through the transrectal route.