Prostate cancer develops in the prostate, a small walnut-shaped gland that is part of a man's reproductive system. Prostate cancer occurs when cells in the prostate gland grow out of control. Cancerous cells first show uncontrolled growth and spread into the prostate. Then it extends into the capsule surrounding the prostate, pierces the capsule and spreads outward from the prostate. Prostate cancer, unlike benign prostate gland enlargement, does not originate from the center of the prostate, but from the region close to the capsule, away from the center. For this reason, urinary complaints in prostate cancer bother the patient at a later stage. During the period of growth and spread, it can spread to nearby organs, the lymph system and other parts of the body through the bloodstream. Prostate cancer has a slow course and the tumor can spread to bones and other organs by showing a very aggressive character.