In front of the bladder is a small organ that looks like a tiny chestnut - the prostate. The urethra runs from the bottom of the bladder right through the middle of the prostate.

Urine continually collects in the bladder  Every so often the muscles at the bottom of your bladder relax, while the muscles surrounding the bladder contract, squirting the urine into the urethra which runs through the prostate and continues through the penis and out of the body.

Situated under the bladder, and wrapped around the urethra, the prostate gland's primary job is to add special fluid to the sperm before it is ejaculated out from the penis. Sperm is produced in the testicles. From the testicles it moves up into the epididymis, where it matures, then into the two small, muscular tubes called the vas deferens, which coil up and around the bladder to the seminal vesicles.

Prostate cancer ordinarily grows slowly but once the cells that make up prostate cancer have grown inside the prostate for a long enough time to reach a critical mass in size and number of cells, the cancer can spread outside of the prostate gland to other parts of the body. Once free of the prostate, the cancer cells can find new homes in the bones, liver, brain, lungs, spinal cord or elsewhere.