The only test for prostate cancer has been declared useless - by its own inventor. So how can men protect themselves from a disease that claims 10,000 lives a year?

The only available test for prostate cancer was last week declared "all but useless" by the Californian professor who developed it 17 years ago. The warning from Professor Thomas Stamey of Stanford University has left men wondering what they should do to protect themselves against the commonest form of male cancer. Professor Stamey's work on the PSA test - for prostate-specific antigen, a protein that can indicate prostate cancer when found in high levels in the blood - has made it a standard worldwide.

When Clive Hilton was diagnosed with prostate cancer three years ago, he thought it would be the end of his marriage and his dignity. "I went to see the consultant for the result and he told me I had got cancer. I asked him what I should do and he said have it out."

The consultant gave him a booklet to read that spelt out the risks of surgery: a 70 per cent chance of impotence and a 5 per cent chance of severe incontinence (not to mention a much higher risk of less severe incontinence). "Surgery looked like a nightmare. I had no symptoms and this huge chance of impotence as a result of the treatment. My wife and I were shaking at the prospect."

A friend suggested he went for a second opinion and he was referred for radiotherapy, recommended as the "least worst option". He was preparing to go through with it when he was offered an escape route.

"I was booked in for the treatment at the Royal Marsden in Surrey when they asked me if I would like to go on their active surveillance programme. The cancer was very small and they said that if at any time it showed signs of growing or spreading they would operate."

Now Hilton has a PSA test every three or four months and a biopsy every two years. So far there is no sign that the cancer is growing - so he has escaped potentially damaging treatment. "I reckon I am going to die with the cancer, not of it. There are men who have been treated because of the test and are impotent and incontinent. It is a fact that the cure is worse than the disease."

He is appalled by the damage that has been done by over-treatment. "If you were given the option of living with cancer or having your sex life removed and being given a nappy to wear, which would you choose?"

Many men would be appalled by the idea of living with a cancer inside them, but he is unworried by it. "I feel like a fraud. I go to the Royal Marsden for my check-ups and there are people undergoing chemotherapy who have lost their hair and have yellow, waxy skin, and I think I shouldn't be saying I have the same disease as these people."

His experience illustrates the unique feature of prostate cancer: it is curable but may not need treatment. In many men it is slow-growing - so slow that they can live with it and die of something else.

Professor Stamey first suggested that a blood test for prostate-specific antigen (PSA) could indicate the presence of cancer in a paper in The New England Journal of Medicine in 1987. The discovery spawned a vast prostate screening industry - nearly a quarter of a million men will be diagnosed with prostate cancer in the US this year - and a huge growth in the number of men treated for the condition. Now, he has recanted, and suggests that the test merely indicates the size of the prostate and may do more harm than good by encouraging over-treatment. Many of the cancers detected by it are too small to be clinically meaningful and many men may have been unnecessarily treated. "The PSA era is over," he said in The Journal of Urology.

However, there are 27,000 new cases of prostate cancer a year in the UK and almost 10,000 deaths. As a killer, it is second only to lung cancer and not far short of breast cancer, which causes 13,000 deaths a year. There is an urgent need for an accurate test that can detect those cancers that are going to turn into killers.

Professor Colin Cooper, head of male cancers at the Institute of Cancer Research in London, welcomes the demise of the PSA test as a method of screening the healthy, asymptomatic population. "The situation in north America has been dreadful," he says. "Annual PSA tests have been introduced by private medicine for men over 50, and 80 per cent take them. That is a pretty horrifying statistic." Not all the men with a high PSA had prostate cancer. Even among those in whom it was confirmed by biopsy, "probably more than half" did not need treatment and the treatment carried serious risks, says Professor Cooper. "In the US they are making tens of thousands of men impotent for no reason. I hesitate to use the word 'scandal' but I can't think of a better word for it. It is beyond belief."

In his view, only men with symptoms - difficulty peeing, a weak stream, or getting up in the night to pee - should have a PSA test. However, one in three men over 50 experience these symptoms anyway, which are often caused by benign enlargement of the prostate and not by cancer. Any man with a high PSA test must therefore be referred for a biopsy to confirm the presence of cancer.

Those in whom cancer is diagnosed then face a difficult choice - to treat or not to treat. Denis Law, the former Manchester United footballer, spoke earlier this year about his experience of being diagnosed with prostate cancer. He had been persuaded to go to his GP by his wife and, when the cancer was discovered, he did not hesitate to have surgery.

But Professor Cooper's advice is that for those with "low-grade, low-volume" tumours in whom the PSA level is not too high, active surveillance may be the best option. The Institute of Cancer Research runs the programme that Hilton is on at the Royal Marsden. "Of the first 80 patients with prostate cancer on the programme, 70 did not need treatment within the first 10 years. That shows how treatment is given unnecessarily in the US."

The crucial task is to develop a better test for prostate cancer - one that can distinguish between the slow-growing, non-threatening tumours and the more aggressive kind. On this score, there is good news. Scientists at the Institute of Cancer Research announced in June that they had identified a gene - E2F3 - that could be the answer. "Now we know that the E2F3 gene is key in determining how aggressive the [prostate] cancer is," says Professor Cooper, "we hope to be able to develop such a test in the next five years."