Cancer is a disease in which abnormal cells in the body grow out of control. Cancers are usually named after the part of the body where the abnormal cell growth begins. Prostate cancers are cancer cells from the prostate. When prostate cancer cells spread to other parts of the body, they are called metastases.
The prostate is a part of the male reproductive system, which includes the penis, prostate, and testicles. The prostate is located just below the bladder and in front of the rectum. It is about the size of a walnut and surrounds the urethra (the tube that empties urine from the bladder). The job of the prostate is to produce fluid that makes up a part of semen.
As a man ages, the prostate tends to increase in size. This can cause the urethra to narrow and decrease urine flow. This is called benign prostatic hyperplasia, and it is not the same as prostate cancer. Men may also have other prostate changes that are not cancer.
This diagram shows the location of the prostate, in front of the rectum and just below the bladder.