A dramatic fall in deaths from prostate cancer in the US has raised questions about Britain's poor performance against the commonest cancer in men.

Deaths from the disease have declined four times faster in the US than in the UK over the past decade, having peaked in both countries in the early 1990s at almost identical rates.

Specialists claim that a combination of screening for early detection of the disease combined with more aggressive treatment is the secret of the US success.

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But sceptics say screening and aggressive treatment come at too high a cost, causing unnecessary suffering to patients who did not need treatment and serious side effects such as impotence and incontinence.

There are 35,000 cases of prostate cancer diagnosed annually in the UK and 10,000 deaths. Simon Collin and colleagues from the University of Bristol, who compared the US and UK, say the differing outcomes are worrying.

"Trends in US death rates in other cancers, such as breast and bowel, have closely followed those in the UK but for prostate cancer they have sharply diverged in the past decade. Something different is happening with prostate cancer," Mr Collin, a statistician, said.

Since the peak in deaths in the two countries in the early 1990s, mortality rates had fallen by 4.2 per cent a year in the US and by 1.2 per cent a year in the UK. In the US, the biggest decline was among men over 75 while in the UK death rates in this age group had plateaued by 2000.

A key difference between the countries lies in the extent of screening with the PSA (prostate specific antigen) blood test. More than half (57 per cent) of men over 50 reported being screened in the past 12 months, compared with 6 per cent in the UK.

In addition, treatment in the US is more aggressive, with a higher use of radical surgery, radiotherapy and hormone treatment.

Mr Collin said: "Prostate cancers are detected predominantly when they are still localised in the US because of screening, whereas in the UK they tend to be picked up later. The big question is: does early detection lead to a survival benefit?"

"It is plausible that early detection and more aggressive treatment does improve survival. The caveat is that you detect a lot of prostate cancer if you look for it and much of it is indolent [not needing treatment]."

Prostate cancer is often slow growing and does not affect the quality or length of the patient's life. In these patients, the treatment may be worse than the disease, Mr Collin said. "The nature of prostate cancer is that you are more likely to die with it than from it."

The authors of the study, published in Lancet Oncology, say the jury is still out on whether screening is worthwhile. It is hoped the results of two trials next year will provide the answer.