Studies cast doubt on the value of prostate screening

Whether to screen middle-aged men for prostate cancer is one of the most controversial issues in oncology.

Screening through the PSA blood test, which detects raised levels of “prostate specific antigen” associated with the disease, can reveal the presence of cancer before symptoms appear, enabling doctors to treat it early through surgery or radiation. In principle this should improve the prospects of a cure.

However the side-effects of treatment are often unpleasant, including impotence and incontinence. And prostate cancers often grow extremely slowly, causing no trouble till the patient dies of other causes.

Now the New England Journal of Medicine has published the results of two huge clinical trials of prostate cancer screening, which were supposed to give doctors better guidance about whether to give the PSA test to symptomless men.

Unfortunately the results are somewhat contradictory. But the overall conclusion seems to be that screening may save a small number of lives but will expose far larger numbers to unnecessary treatment and psychological stress.

A European study of 162,000 men, observed for an average of nine years, found a 20 per cent reduction in mortality among those given the PSA test. For every life saved, however, 1,400 men were screened and 48 men received treatment following a positive result. A US study of 77,000 men, followed for seven years, resulted in more detections of disease but no survival benefit from screening.

John Neate, chief executive of the UK-based Prostate Cancer Charity, says the research “highlights the critical importance of the development of a scientific test that can identify aggressive forms of prostate cancer and differentiate them from slow growing forms of the disease. Such a test would enable treatment to be focused on men for whom prostate cancer poses a serious risk to their health and avoid the over treatment of men with the harmless, slow growing forms of the disease.”

Until a much improved test is available, the middle-aged writer of this blog will decline any invitation to be screened for prostate cancer.

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Clive Cookson, the FT's science editor, picks out the research that everyone should know about, in fields from astronomy to zoology. He also discusses key policy issues, from R&D funding to science education. He'll cover the weird and wonderful, as well as the serious side of science.