What is prostate cancer?

Prostate cancer is a malignant tumour of the prostate gland, a small gland found only in males. Prostate cancer occurs mainly in men aged over 50 years and is the most common cancer among New Zealand men, with around 3000 cases diagnosed each year. Prostate cancer is the third highest cause of cancer deaths in New Zealand men (after lung cancer and bowel cancer).

What is the prostate?

The prostate is a small gland, normally about 4cm across, 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, and semen from the sex glands, to the penis.

The prostate produces most 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 (testicles).

It is common for the prostate gland to get larger as men grow older. This enlargement is called benign prostatic hyperplasia (BPH). This condition is the usual cause of the urinary symptoms that older men complain of, and prostate cancer is only occasionally responsible for these symptoms.

Can prostate cancer spread?

Early prostate cancers are contained within the prostate gland and are called 'localised' cancers. Spread of the cancer to the surrounding tissues is known as extracapsular spread, and these tumours are described as being 'locally advanced'.

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.

What causes 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

 See Diagnosing prostate cancer and Treatment of prostate cancer

What does that term mean? See Cancer glossary

Original material provided by the Cancer Society of New Zealand, 2008. Reviewed and edited by everybody, July 2010.