Single PSA test predicts prostate cancer mortality risk

By Lilian Anekwe

A single PSA test at age 60 strongly predicts a man's lifetime risk of developing and dying from prostate cancer, according to a BMJ analysis.

41271022The study – of 1,167 Swedish men who had PSA measured when they were 60 and were then followed up for 25 years - found that 90% of deaths from prostate cancer occurred in men with highest PSA levels at age 60. But men with average or low PSA levels had negligible rates of prostate cancer or death by age 85.

The results suggest men with a PSA of 1 ng/ml or less aged 60 need not have another PSA test, reducing over-diagnosis and over- treatment.

Although only a minority of the men who had a PSA level of over 2ng/ml when tested in 1981 went on to die of prostate cancer, 90% of the metastases and 95% of the deaths occurred in these men.

But men with PSA concentrations at or below the median of 1ng/ml were unlikely to develop clinically relevant prostate cancer – these men had a 0.5% risk of metastasis by age 85 and 0.2% risk of death from prostate cancer.

Lead researcher Dr Andrew Vickers, a researcher in epidemiology and biostatistics at the Memorial Sloan-Kettering Cancer Center in New York, concluded: ‘Though men aged 60 with concentrations below 1 ng/ml might harbour prostate cancer, it is unlikely to become life threatening. Such men could be exempted from further screening, which should instead focus on men with higher concentrations.'

Screening for prostate cancer is contentious - both in the US and the UK – but PSA testing is more popular in the US with a third of men aged between 50 and 64 being screened annually.

Dr Jonathan Rees, a urology GPSI in Bristol, said the study was small compared to other PSA studies but added: ‘We are constantly asked for testing and when the results come back inevitably the question is always "when should I have another one"?'

‘This study suggests that younger patients with higher PSA levels are the ones we need to focus on but older patients with a PSA of less than 1ng/ml are much less at risk.'

A spokesperson for the UK National Screening Committee said the research would feed into their ongoing review of prostate cancer screening policy, due to compete in March.

But Dr James Kingsland, a GP in Wallasey, Merseyside, and member of the government's scientific advisory group on prostate cancer risk management, said: ‘This certainly adds to the debate but does not give us the necessary evidence to start a national screening programme using PSA testing. It is also unclear how this Swedish study could be applied to the now diverse UK population.'

A second systematic review and meta-analysis, also published in the BMJ, ruled out a population-wide prostate cancer screening programme, after failing to find evidence from six randomised controlled trials of nearly 400,000 men. Instead they suggest GPs should inform men about the uncertainties associated with screening.