Why the PSA test is not pointless

The PSA test has long been considered the first line of defence against prostate cancer. A simple blood test, it measures the level of PSA (Prostate Specific Antigen) in the blood. All men have some PSA in their blood, which is made by the prostate gland. High levels can indicate prostate cancer.

This week, the Academy of Medical Royal Colleges published a list of 40 tests and medical procedures which they said people did not really need, including the PSA test. They said that these tests do not lead to a longer life unless you are a man with a family history of the disease of belong to a ethnic group which is more at risk.

However, many experts believe that they are basing this opinion on bad science.

According to Professor Chris Eden, consultant urologist at the Royal Surrey County Hospital in Guildford, a PSA test is principally a ‘pointer’ which can help identify men who need further investigations. ‘Around 25 per cent of men with a PSA score of between 4-10 will have cancer and around 40 per cent of men who have a PSA test over 10 will have prostate cancer,’ he says.

Despite this, he is deeply alarmed about the new Academy of Medical Royal Colleges advice. ‘There is no scientific evidence to back up their view that PSA tests fo not help to reduce mortality caused by prostate cancer. In fact, the opposite is true.’

Prostate cancer is the second most lethal cancer in men, after lung cancer and one man dies every hour in the UK from the disease.

He points to a large-scale study called the European Randomised Study of Screening for Prostate Cancer which involved 182,000 men and followed them for over a decade. ‘The findings, which were published in 2009 found that men who were screened with PSA tests had a 20 per cent reduction in prostate cancer related deaths compared to men who were not screened after 11 years. In a subset of Swedish men who were followed for 14 years, the difference was even more startling – the reduction in deaths was 44 per cent in the screened group of men.  Professor Eden believes that the Academy of Medical Royal Colleges is basing their advice on a US study called the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial which also reported in 2009, which was much smaller and he say, has some major flaws. Critically, it reported after just seven years, which is meaningless in terms of prostate cancer which is often slow growing and can take years to reveal itself.

‘The main problem with the PLCO study is the high level of contamination in the control arm: 90 per cent of men had a PSA when none of them should have had this test. This level of contamination is much higher than was previously (before May 2016) believed, when we thought it was around 40 per cent.  Because of this, and other, serious methodological flaws the study effectively contributes nothing to the debate on PSA screening but is still used as a reason not to screen.’

In the UK, there is no nationwide screening programme as such, but men who have concerns can ask their GP about PSA testing.