Prostate cancer screening could reduce deaths from the disease by about a fifth, according to a major European study.

However, the authors of the study of over 162,000 men conclude that routine blood test (PSA test) screening programmes for prostate cancer should not be introduced at this time.

Doubts remain as to whether the benefits of screening outweigh the risks. The risks include treating men with very slow-growing tumours unnecessarily.

The European Randomised study of Screening for Prostate Cancer (ERSPC) began in 1993 to find out whether screening men for prostate specific antigen (PSA) in the blood, which can indicate the presence of cancer, reduces deaths from prostate cancer.

It recruited men between the ages of 50 and 74 years from eight countries (Belgium, Finland, France, Italy, Netherlands, Spain, Sweden, and Switzerland) who had either PSA screening every four years (2 years in Sweden), or no testing (control group).

Men were referred for a biopsy if their PSA concentration was regarded as high.

The results showed that PSA screening appeared to reduce prostate cancer deaths by 15% at nine years, and this improved to 22% at 11 years.

Over 13 years follow-up, there was no further improvement in the reduction in deaths, which dropped by roughly a fifth (21%) in the screening group compared with the control group, although men who were screened had a 27% lower chance of dying of prostate cancer.

However, it was found that the absolute benefit of prostate screening steadily increased with longer follow-up.

The number of men needed to be invited for screening to prevent one death from prostate cancer dropped from 1,410 after nine years of follow-up to 781 at 13 years. The number needed to be diagnosed and treated to prevent one prostate cancer death also fell, from 48 to 27.

The researchers believe screening can deliver a substantial reduction in prostate cancer deaths, similar or greater than that reported in screening for breast cancer.

However, they warn that over-diagnosis occurs in roughly 40% of cases detected by screening, resulting in a high risk of over-treatment and common side-effects of surgery such as incontinence and impotence.

Prof Fritz Schroder from Erasmus University Medical Centre in the Netherlands, who led the study, said:"The time for population-based screening has not arrived. Further research is urgently needed on ways to reduce over-diagnosis preferably by avoiding unnecessary biopsy procedures, and reducing the very large number of men who must be screened, biopsied, and treated to help only a few patients."

"One promising approach is multiparametric MRI technology, which may be able to selectively diagnose aggressive prostate cancers and avoid the diagnosis of many inconsequential tumours that generally grow so slowly that most men will die of other causes. But for now, men must to be given well-balanced information including the screening harms of over-diagnosis and over-treatment."

The PSA test can sometimes be a sign that prostate cancer it present, but this can only be confirmed by taking a sample tissue (biopsy) from the prostate gland.

The research is published in The Lancet journal.

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