Prostate cancer is a malignant tumor of the prostate gland, a walnut-sized organ located in front of the rectum and right below the bladder. The function of the prostate gland is to produce part of seminal fluid, the solution that carries sperm.
Like all cancers, prostate cancer is a disease of uncontrolled cell growth. Cells become cancerous when they divide unpredictably and form tumors. As tumors grow, they squeeze surrounding healthy tissue and use oxygen that would normally be used by healthy cells. They also secrete protein signals that initiate the formation of new blood vessels for the tumor. As a prostate tumor grows, it may spread to the entire prostate gland or to lymph nodes, other organs, or bone.