Prostate cancer develops in the prostate, the muscular, walnut-sized gland that's located below the bladder and in front of the rectum. The prostate makes the thick fluid that’s part of semen and plays an important role in both sexual function and urinary function.
As a man ages, the cells of his prostate may change and form tumors or other growths. Cancer cells, in particular, grow out of control and spread beyond the prostate. Cancer that spreads is harder to treat.