Cells in any part of the body can become cancer cells, and can spread to other parts of the body.
It starts when cells in the prostate gland grow out of control. The prostate is a gland found only in men, which produces some of the fluid that is part of semen.
In front of the rectum (the last part of the intestines), the prostate is located below the bladder (the hollow organ that stores urine). A gland known as a seminal vesicle makes most of the fluid for semen just behind the prostate. As the tube that carries urine and semen out of the body through the penis, the urethra passes through the center of the prostate.