Catching a killer can do more harm than good

Screening for prostate cancer is not a priority - and yet 10,000 men die from the disease each year. But early detection may not be the answer, says Rob Stepney

When David Sullivan, a 63-year-old businessman, went into hospital last August to have his kidney stones removed, the last thing he expected was to be told he had suspected prostate cancer. But a routine check- up for levels of prostate specific antigen (PSA) in the blood revealed that Mr Sullivan's level of PSA was 10 times higher than average. A second PSA measurement a month later was higher still. Examination of tissue samples from the prostate suggested that cancer was present in half the gland.

"Finding my cancer early was down to luck," he says. "All women have the option of breast screening, and I don't see why men should be denied the same chance."

Mr Sullivan was, indeed, lucky. Of the specifically male tumours, prostate cancer is by far the biggest killer, with almost 10,000 British men dying from it each year - only 3,000 fewer than the number of women killed by breast cancer. Yet improving its treatment has not been a priority, and experts are deeply divided over whether the screening for prostate cancer that probably saved Mr Sullivan's life could save others.

For an obscure, plum-sized gland at the base of the bladder, with the modest role of contributing fluid to semen, the prostate can cause a lot of trouble. In many old men, enlargement of the gland, which surrounds the urethra, leads to difficulty with urination and surgery may be required. Cancer of the prostate is less common than benign enlargement of the gland, but it is life-threatening. In half of all cases, by the time the disease is diagnosed the tumour has already spread to other parts of the body - typically the bones.

Yet a simple and reasonably accurate screening test for prostate cancer is available. All it requires is a small blood sample in which to measure the level of the protein PSA. Recent work from St Bartholomew's Hospital, London, shows that apparently healthy men subsequently diagnosed with prostate cancer have abnormally high levels of PSA.

But not everyone is convinced of the benefits of PSA testing. There are two problems. First, most small prostate tumours progress very slowly, and many older men who have them die of other causes long before their prostates pose a serious problem. "Screening will pick up four times more cancers than would ever cause a problem clinically," says David Neal, professor of surgery at the University of Newcastle.

As yet, specialists cannot distinguish between the slow-growing prostate cancers that could safely be left alone and those that should be treated. If doctors intervened in all the cases of early prostate cancer detected through screening, only the small number of men with potentially fast- growing tumours would benefit. The far larger number with less aggressive disease would experience the side-effects of radical treatment for no good reason. Removing the prostate gland is a serious operation which carries a high risk of impotence and a small risk of incontinence.

David Kirk, a consultant urologist at Gartnavel General Hospital in Glasgow, points out that whereas small breast tumours picked up by screening can often be removed by relatively simple surgery, "with prostate cancer, even if the tumour is small, any treatment which aims at cure involves substantial risk of side-effects". Because of this, comparing breast and prostate cancer screening is misleading, he argues.

A second point is that doctors do not know how best to treat early-stage prostate cancer. There are three possible approaches: radical surgery, in which the entire prostate is removed; radiotherapy, and "watchful waiting" which means, essentially, doing nothing unless there is evidence that the cancer is progressing. No properly conducted study has ever compared the results of aggressive treatment with no treatment at all.

Until there is evidence that active intervention improves life expectancy, there is no point in screening for the disease, conservative urologists argue. Some even believe screening is unethical. One surgeon (who did not wish to be named) says: "People generally think it a good thing to catch a cancer early, but they're not told that if a prostate cancer is diagnosed they will have to make the terribly difficult decision between treatment and doing nothing, when there is no treatment of proven benefit."

Robert Shearer, consultant urologist at the Royal Marsden Hospital, London, says that while it would be premature to introduce a national prostate screening programme, properly controlled studies are needed to determine whether screening could save lives. One such trial is in progress in Europe but it may be 10 years before we know the results. "I'd like the UK to help with that trial," says Mr Shearer. "It is lacking in vision for us not to be involved in one of the most important men's health issues of the next 20 years. Unfortunately, we don't have the necessary resources."

One of the most prominent advocates of screening is Roger Kirby, a consultant urologist at St George's Hospital, London. He believes this country should embark on its own trial, and proposals have been drawn up for such a study in the South-west Thames health region. "But the older I get, the more resigned I am, and I have no great hope it will be funded by government," he says.

Mr Kirby agrees that the best treatment has still to be decided. "But 10,000 men die of the disease each year. And if one of them happens to be your father, or if you yourself are eventually found to have advanced disease, you will probably feel there should have been a screening blood test done."

"The benefit of surgery has not been proved beyond reasonable doubt. But if you've done all the screening tests and know a cancer is there, the logical thing is to take it out. I know that I can remove the prostate and the lump with it and that the patient will not die of prostate cancer ... more conservative people would say I don't know that the patient wouldn't have done well anyway."

Radiotherapy, an alternative to surgery, kills only half of the tumours treated, he says.

Faced with such diversity of opinion among experts, the Government has chosen to sit on the sidelines. It says: "The case for a national programme has not been established." In this instance, at least, official reluctance to act on screening may be based not on penny-pinching but on a realistic appraisal of our current ignorance and of the idea's limited chance of success.

Information on prostate cancer is available from the Imperial Cancer Research Fund, PO Box 123, Lincoln's Inn Fields, London WC2A 3PX and the Royal College of Surgeons, 35 Lincoln's Inn Fields, London WC2A 3PN. The Prostate Research Campaign UK, 36 The Drive, Northwood, Middlesex HA6 1HP.