A STUDY in the BMJ suggesting that a single prostate-specific antigen (PSA) test at age 60 strongly predicts the lifetime risk of diagnosis and death from prostate cancer has been welcomed by Australian experts.(1)

The study involved 1167 men born in 1921 who, in 1981 and at age 60 years, all provided blood samples for the Malmo Preventive Project in Sweden. After 25 years of follow-up, it was found that 90% of prostate cancer deaths had occurred in those who had the highest PSA levels at age 60.

The authors said although men with low levels might have prostate cancer, it was unlikely to become life threatening and they could be exempted from further screening. Screening programs could then focus only on those with higher PSA levels.

Dr David Malouf, president of the Urological Society of Australia and New Zealand, praised the Malmo study for showing that it was possible to identify men at 60 who may not need to undergo further testing.

However, he noted that these data needed to be validated in Australia. Dr Malouf also said that a one-off test at age 60 would still miss a lot of significant cancers in younger men.

“A PSA above median at the age of 40 (0.6 ng/ml) identifies a high-risk population and, at the other end of the spectrum, a low PSA at the age of 60 (below 1.0 ng/ml) identifies a low-risk population,” he said.

Associate Professor Alexandra Barratt, of the University of Sydney’s School of Public Health, applauded the study for exploring a way to reduce the devastating impact of overdiagnosis and overtreatment often attached to PSA screening.

She suggested a one-off screen at age 60 might ease this, but noted that the relatively small nested case-control Malmo study was done in a population very different from Australia’s.

Dr Malouf said the official Urological Society policy did not advocate population-based screening for prostate cancer.

“There is still information on quality of life and the cost effectiveness of PSA screening that need to be taken into consideration,” he said.

He pointed to flaws in a second study published at the same time in the BMJ, a meta-analysis of six randomised controlled trials which found that screening helped in the diagnosis of prostate cancer at an earlier stage but did not have a significant impact on mortality.(2)

The only two studies in the meta-analysis with good design and adequate follow-up had found that PSA screening did reduce the risk of dying from prostate cancer, both he and Professor Barratt said.

According to Professor Barratt, this had to be weighed against the burden of overdiagnosis.

An accompanying editorial in the BMJ said that, for now, clinicians were best advised to individualise their approach to PSA screening.(3)

1. BMJ 2010; 341: c4521.

2. BMJ 2010; 341: c4543.

3. BMJ 2010; 341: c4538.

Posted 20 September 2010

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