Early PSA screening may reduce risk of prostate cancer death: study

TORONTO (CP) - Early screening for prostate cancer in men without symptoms could significantly reduce their risk of going on to develop an advanced and usually deadly form of the disease, a Canadian study suggests.

Researchers at the universities of Toronto and British Columbia found that early PSA testing may reduce the risk of metastatic prostate cancer - the kind that spreads beyond the walnut-sized gland - by more than a third.

The study compared the PSA testing histories of 236 men with advanced prostate cancer against those of a control group of men without metastatic cancer - 462 who either didn't have the disease at all or had a localized tumour.

"What we found was, in fact, that the risk of metastatic prostate cancer was about 35 per cent less in the men who had been screened," said study co-author Dr. Vivek Goel, a professor of health policy management and evaluation at the University of Toronto.

The screening tool is a simple blood test that detects levels of what's known as prostate specific antigen, or PSA. While small amounts in the blood are normal, higher levels could indicate cancer.

Yet the test remains controversial because it is not foolproof and may cause undue distress. High PSA levels can exist when no cancer is present or a tumour may be a type that doesn't spread to other parts of the body, so men can live normal lives for many years to come.

But PSA testing may also flag the type of prostate cancer that will go on to spread if left untreated, said the researchers.

"Our study . . . adds to the body of evidence that shows that it does have potential for having a fairly significant effect in reducing the risk of advanced prostate cancer and, by extrapolation, the death from prostate cancer," Goel said.

That's because detecting prostate cancer before it has spread allows for early and effective treatment.

The study adds weight to the argument that PSA testing should be routine for men - as mammography and pap smears are for women - not just when a doctor suspects cancer because of symptoms, he said. "There may be greater benefit from an organized screening program."

But the test, when used strictly as a screening tool, is covered by only about half of Canada's provincial health plans.

An estimated 20,500 Canadian men will be diagnosed with prostate cancer this year, and about 4,300 will die. Prostate cancer is the second-highest cause of cancer death among North American men after lung cancer.

"Our study shows a fairly significant benefit for early screening using the prostate specific antigen test, so these results are important for men and their doctors," said Dr. Jacek Kopec, professor of health care and epidemiology at the University of British Columbia and lead author of the paper.

The head of the Canadian Cancer Society, which helped fund the study, called the findings welcome news for Canadian men.

"The results of this study are interesting and add to the body of evidence about the PSA test," said Dr. Barbara Whylie.

"We look forward to the results of two other large, ongoing trials to validate these findings," Whylie said in a statement. "In the meantime, we will continue to encourage men to discuss this test with their doctors until more definitive answers about the benefits of the PSA test are available."

The study, published in the August issue of the Journal of Urology, recruited men from the Greater Toronto Area in 1999-2002. They ranged in age from 45 to 84; the average age of prostate cancer diagnosis was 68.

Researchers obtained self-reported information about their lifestyles, health history and use of health services. They also received permission to review medical records and history of PSA screening.