Scientists cast doubt on value of screening for prostate cancer

Apr 17 2008

Even though deaths from prostate cancer death have fallen in the U.S. since screening became more common, new research is suggesting that this does not justify the need for such tests.

According to a team of scientists from the University of Bristol many other factors could be involved such as different treatment programmes for American men and some discrepancy over how deaths are reported.

Since screening became widespread in the U.S. mortality rates have fallen four times more than in the UK.

It seems that many men over 80 have evidence of prostate cancer when they die, but it is often unclear whether this or other conditions killed them, which leads to different accounts on death certificates.

The researchers say this does not mean that screening by using a blood test to detect what is known as the prostate specific antigen (PSA), is not saving lives.

But they suggest until research pins down the exact role of screening in decreasing prostate cancer mortality, it remains a matter of speculation.

Whereas prostate cancer screening became common in the States in the early 1990s, and nearly 60% of men over 50 were being tested by 2001, in the UK, between 1999 and 2002, an estimated 6% of men aged 45-84 had been tested.

At the start of the 90s, mortality rates for the two countries were similar, but after this period, the rate of decline in the U.S. at 4.17% per year, was almost four times that of the UK, at 1.17% per year.

Simon Collin a statistician who led the research says other changes were occurring in the treatment of men with prostate cancer in the U.S. during that time and included the use of a particular hormone treatment in older men and more aggressive treatment of those with an advanced form of the disease.

Prostate cancer accounts for a quarter of cancers in men but the National Health Service (NHS) has resisted offering widespread PSA screening because the test is seen as notoriously inaccurate.

Even though 10-15% of men will have high enough PSA levels to justify carrying out a prostate biopsy, only 2-3% will require any treatment.

This means in fact that the majority will have been subjected to unpleasant, invasive and potentially costly investigations for no reason with possible serious side effects such as impotence and incontinence.

Experts say there is an urgent need for a new diagnostic test which could form part of a national screening programme and which would reliably identify the aggressive prostate cancers that need treatment.

The NHS says all screening programmes are based on an assessment that more good than harm will be achieved through their implementation and until there is clear clinical evidence to show real benefit can be gained from routine prostate screening, the NHS will not be screening men who have no symptoms for prostate cancer.

The authors of the study say while the differing outcomes are worrying, the jury is still out on whether screening is worthwhile.

The research is published in Lancet Oncology.