What is the prostate?

The prostate is a small gland about the size of a walnut, found only in men. It sits just below the bladder and surrounds the top part of the urethra, the tube that takes urine from the bladder to the penis.

The prostate produces some of the fluid that makes up semen. The growth and development of the prostate depends on the male sex hormone, testosterone, which is produced by the testes.

It is common for the prostate gland to get larger as men grow older. This enlargement is called benign prostatic hyperplasia (BPH). This is not cancer, even though the symptoms of BPH may be similar to those of prostate cancer.

What is prostate cancer?

Prostate cancer is a malignant tumour of the prostate gland. Very early prostate cancers are contained within the prostate gland and are called localised cancers. These early cancers do not usually produce symptoms and may not develop into a serious cancer. Such cancers may not require treatment.

However, some prostate cancers grow within the prostate gland and spread to the surrounding tissues. This is called invasive prostate cancer. There is a collection of small lymph glands near the prostate that are part of the lymphatic system, one of your body's natural defences against infection.

Lymph glands filter out bacteria and other harmful agents. A network of very thin lymph vessels connects the major lymph glands in your abdomen, pelvis, groin, neck and armpits.

Cancer that develops in the prostate may spread (or metastasise) via the lymphatic system or bloodstream to other parts of the body, such as the bones.

It is important to note that some men with prostate cancer do not experience symptoms or are not aware of the significance of some of the symptoms they may have experienced.

How common is prostate cancer?

Prostate cancer occurs mainly in men aged over 65 years and is the most common cancer among New Zealand men. Around 2000 to 3000 men are diagnosed with prostate cancer in New Zealand each year.

Causes of prostate cancer

The causes of prostate cancer are not yet fully understood but the risk of developing prostate cancer increases with age. The risks are also higher if other family members have developed this cancer.

There is some evidence to support the idea that a diet high in animal fat increases the chance of developing prostate cancer.

While it is not possible to make clear recommendations about a particular diet, a lower fat, high fruit and vegetable diet is linked with a reduced risk of a number of chronic diseases and is an overall recommendation towards improving health.

Related topics

How does cancer form? For more information on cancer, see What is cancer?

How is prostate cancer diagnosed? See Diagnosing prostate cancer

What treatments are there for prostate cancer? See Treatment of prostate cancer

What does that term mean? See Cancer glossary

Original material provided by the Cancer Society of New Zealand, 2001. Reviewed by everybody, February 2005.