Thursday 16 September 2010
A one-off prostate-specific antigen (PSA) level test at age 60 appears to provide an indication of a man's lifetime risk of being diagnosed and dying from prostate cancer, US scientists have found.
The majority of clinical trials conducted to date have concluded that routine population-wide screening for prostate cancer with the PSA test is unlikely to be of benefit.
Many men with high levels of PSA turn out not to have prostate cancer and the test cannot differentiate between men with aggressive cancer and men whose tumours will never pose them problems.
But the latest research from the Memorial Sloan Kettering Cancer Centre in New York, published in the British Medical Journal, suggests that a single test at age 60 might help to minimise these problems.
The research team, led by Drs Andrew Vickers and Hans Lilja, analysed data on 1,167 Swedish men, all of whom were 60 in 1981. Participants provided blood samples at the start of the trial and were followed up to age 85.
Over the course of the study period, 43 men developed advanced prostate cancer, while 35 men died from the disease.
Researchers found that 90 per cent of prostate cancer deaths occurred in men who recorded the highest PSA levels at age 60.
Meanwhile, men with low or average PSA levels at age 60 only had a 0.5 per cent risk of developed advanced prostate cancer by their 85th birthday, and a 0.2 per cent risk of dying from the disease.
The study authors claim that at least half of over-60s - those with low PSA levels - could be exempted from further prostate cancer screening. Even if these men develop prostate cancer, it is extremely unlikely to be life-threatening.
Meanwhile, those with high PSA levels at age 60 may benefit from additional screening in case they develop the disease, they said. However, even within this group, only a minority of men go on to develop fatal prostate cancer.
Dr Vickers said, "We know that screening detects many prostate cancers that are not harmful, leading to anxiety and unnecessary treatment. It is our ability to determine the risk of the really aggressive cancers that makes this approach of such great potential value."
Writing in an accompanying editorial, Dr Gerald Andriole, chief of urologic surgery at Washington University School of Medicine, said that PSA testing should be tailored to an individual's risk.
Dr Andriole suggested that young men with a strong family history of prostate cancer and those with high PSA levels should be tested on a regular basis. In contrast, elderly men and those with a low risk of the disease could be tested less often, if at all.
The scientist said: "Approaches such as these will hopefully make the next 20 years of PSA-based screening better than the first 20." However, he also added, "Ultimately, early detection of prostate cancer relies on finding more specific biomarkers."
Ed Yong, head of health evidence and information at Cancer Research UK, said: "The PSA test isn't suitable for a nationwide screening programme for prostate cancer. It's unclear whether widespread PSA testing would save lives and it would come at the cost of many people undergoing unnecessary tests and treatments, including invasive surgery with serious side-effects.
"There might be ways of minimising these problems by only testing specific groups of people with a higher risk of prostate cancer, such as men over 60. But even within this group, only a small minority of men with high PSA levels develop fatal prostate cancer. It's important that we find better ways of detecting aggressive prostate cancer at an early stage, a goal that Cancer Research UK scientists are pursuing."
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