HEALTH / Second Opinion

CANCER of the prostate gland is in many ways the male equivalent of breast cancer, yet it has a far lower public profile. Should screening tests be introduced? Can men do anything to reduce the risks? These issues were reviewed recently in the British Medical Journal (BMJ).

Around one man in 15 eventually develops symptoms of prostate cancer and nearly 9,000 men die from it each year in England and Wales. These figures are not very different from the rates of breast cancer in women, though many of the 10,000 and more women who die from breast cancer each year do so before the age of 60, whereas prostate cancer is a disease of elderly men. Careful examination of men aged 75 or over after death from any cause shows that 35-40 per cent have unsuspected cancer within their prostate glands; as men are living longer, more will reach their 80s and 90s and will become aware of cancer.

Irrespective of age, the disease is becoming more common worldwide, with figures suggesting a 15 per cent rise in five years in the mid-Eighties. In the United States prostate cancer is twice as common in black men as in white; whether this is true in Britain is not known since our mortality and health statistics are not classified by race.

The problem for cancer experts trying to reduce mortality from cancer of the prostate is that most of the men who have the disease will not die from it and many will never even have any symptoms. Screening tests are available: a simple physical examination of the rectum by a doctor will detect early enlargement and hardening of the gland; ultrasound and magnetic resonance imaging (MRI) will identify quite small tumours, and a blood test measuring the level of a substance called prostate specific antigen is another useful screen. The current estimate is that about 1.5-2.5 per cent of men aged 50-70 would be found to have symptomless cancers if they were screened using a combination of tests. Whether or not all these men should be offered treatment is far from clear, and the BMJ review calls for a controlled research study to answer the question.

Several research studies have shown that as few as 20 per cent of men diagnosed as having early prostatic cancer go on to die from it - because most are elderly and die of other causes first. Aggressive treatment (using surgery or radiotherapy) makes sense for men who seem likely to live longer than 10 years, but men with a shorter expectation of life may be better served with treatment (with side-effects such as impotence) only if the cancer shows signs of worsening. Even when the cancer has spread, it is often controllable for a year or two by blocking the action of male sex hormones.

What can men do to reduce their risk of developing prostatic cancer? There is evidence that a low-fat diet with plenty of green vegetables may help (as it does for most cancers). Exposure to cadmium or radiation at work increases the risk. Men who have multiple sex partners may be at increased risk. Cancer of the prostate sometimes runs in families. All of these influences are rather vague, and the emphasis is likely to remain on research aimed at defining the optimum age and frequency for screening tests.