The Current

Early cancer screening can lead to unnecessary treatment and side-effects, study suggests

CBC Radio

March 08, 2018

A surgeon performs a robot-assisted prostate tumorectomy. Prostate cancer is the most commonly diagnosed non-skin cancer in men and is usually not life-threatening. (Jeff Pachoud/AFP/Getty)

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A new study suggests that early testing for prostate cancer may not affect mortality rates.  25:00

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Early screening for prostate cancer can lead to unnecessary treatment, and nasty side-effects, according to a new study.

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Richard Martin, Professor of Epidemiology at the University of Bristol, ran a 10-year, randomized study of PSA testing, involving more than 400,000 men aged 50-69.

Researchers extended a single invitation to men from across the U.K. to undergo PSA screening, a blood test that measures the presence of a protein called prostate-specific antigen, which all healthy men have.

Men who showed raised PSA levels were invited to have a biopsy, which is required to make the firm diagnosis of prostate cancer.

They found that the level of detecting prostate cancer was higher in those who had been invited to the test (the intervention group), than those who were not invited (the control group). But the mortality rate between the two groups was the same.

"The crucial finding was that there was no difference in the number of men who died of prostate cancer," he says of the results, which were published in the Journal of the American Medical Association.

"0.3 per cent of men died in both groups, after the ten-years follow up."

Side-effects

Some prostate cancers are indolent, and harmless, Martin says, while others are aggressive and can kill.

PSA testing highlights both, but cannot distinguish between them. Martin says we also can't tell if a harmless cancer will develop into a dangerous one.

This means patients could undergo treatment for a cancer that would never have harmed them — and living with incontinence, impotence and other health implications as a result.

Stuart Edmonds, vice president of research, health promotion, and survivorship at Prostate Cancer Canada, says that the alternative to treatment is active surveillance.

"You monitor and you don't treat, you only treat the ones [where] the PSA rises or where the biopsy suggests that something suspicious is happening."

He agrees that better testing is needed.

"PSA isn't a bad entry point, but it's not a diagnostic," he says, noting that results from biopsies and MRIs are improving all the time.

"We need to do better at diagnosing the aggressive forms of disease — the disease that a man will die of, rather than the disease that a man will die with."

Listen to the full conversation — which includes a conversation with Lorraine Hulley, president and founder of Pro Health Navigators Canada, on how patients can better understand conflicting medical information. 

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This segment was produced by The Current's John Chipman and Samira Mohyeddin.