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U.S. task force recommends against routine PSA screening for prostate cancer

05/21/2012 05:13 EDT | Updated 07/21/2012 05:12 EDT
TORONTO - Routinely screening men for prostate cancer with PSA tests can result in far more harm than good, says a U.S. expert panel in a recommendation against the practice that is sure to fuel continued debate over the issue.

On Monday, the U.S. Preventive Services Task Force released its final recommendation, advising against routine PSA blood tests to detect possible prostate cancer, the third most common cause of cancer death in North American males after lung and colorectal cancer.

Having an elevated level of PSA, or prostate-specific antigen, can flag the presence of cancer. But it can also be a sign of a benign enlarged prostate or infection, and most men who have a biopsy in response to an abnormal PSA test don't end up having cancer.

Often when prostate cancer is found through screening, the tumour is small and too slow-growing to be harmful, and many men end up dying of another cause. Yet there's no way of knowing which tumours are potentially deadly — requiring aggressive treatment — and which are not.

Almost all men with PSA-detected prostate cancer opt to receive treatment. Besides complications from the biopsy, there can also be serious adverse effects from treatment.

"It's important for doctors and patients to understand that our current approach to screening for prostate cancer does not serve men well," said task force chair Dr. Virginia Moyer.

"Basically out of 1,000 men who are screened, one man will not die of prostate cancer who otherwise would have died of prostate cancer," said Moyer, a professor of pediatrics at the Baylor College of Medicine.

"The recommendation is that men not be routinely screened for prostate cancer using PSA," she said from Houston. "We came to that conclusion because the science now is that there is at most a very small benefit — and that is actually not a certain benefit."

The group's final recommendation, published in this week's Annals of Internal Medicine, follows a similar draft statement in October and consideration of subsequent public comment. The advice applies to men of all ages, but not to those who have been diagnosed with or are being treated for prostate cancer.

As part of its research review, the panel considered two large trials of PSA screening in men without any symptoms to assess the test's life-saving benefits. The first trial, conducted in the U.S., found no drop in prostate cancer deaths. The second, conducted in seven European countries, found about one death in 1,000 was prevented in men aged 55 to 69 years, mostly in two countries.

But research also shows screening can lead to significant harms. Almost 90 per cent of men with PSA-detected prostate cancer undergo early treatment with surgery, radiation or hormone-deprivation therapy.

Up to five of every 1,000 men treated will die within a month of the surgery and at least 200 to 300 men in 1,000 will suffer such life-long effects as urinary incontinence, sexual impotency and bowel dysfunction following surgery and radiation therapy.

"It's not just that your personal risk is higher," said Moyer of individual men. "It really means that across a population, you're asking for a pretty significant sacrifice."

But Dr. William Catalona, medical director of the U.S. Urological Research Foundation, believes the task force has underestimated the benefits and overestimated the harms of PSA screening.

In an accompanying editorial, Catalona and his co-authors argue that the panel — which he said does not include urologists or cancer specialists — based its recommendation on flawed studies with inadequate followup time.

"We don't disagree that there are harms — there's anxiety and side-effects from treatment — but we think that they are exaggerated and many are short-lived," the Chicago urologist said by phone. "And studies have shown that patients who are successfully treated have a very good quality of life."

Catalona suggested that if PSA testing is done "in an intelligent way," prostate cancer deaths could be cut in half. This year, 28,000 American and 4,000 Canadian men are expected to die of the disease.

While acknowledging the test is far from perfect, "there really is no other way out there to detect prostate cancer when it's curable," he said. "So it's an extreme, harsh recommendation.

"It undermines the credibility of the PSA test. So even for men who decide to get tested, if their PSA starts rising and their doctors tell them they need to have a biopsy, and they don't want to have the biopsy, they may sort of disregard the importance of that.

"I think men should not pay any attention to this message ... I think that they should ignore it."

Prostate Cancer Canada also supports widespread PSA testing.

"We know that if prostate cancer is detected early, the number of guys that can be cured of prostate cancer is in the 90 per cent range," said Stuart Edmonds, senior vice-president of research for the advocacy organization.

Those with a high risk of prostate cancer — including black men and those with a family history of the disease — are more likely to be offered the test, which is covered by some but not all provinces. But Prostate Cancer Canada believes the practice should be expanded.

"We encourage men over the age of 40 to initiate a conversation with their family physician at their annual checkup to provide PSA testing and a digital rectal examination," Edmonds said.

Moyer said the USPSTF's received about 3,000 comments from the public, health professionals and advocacy groups in response to its draft recommendation.

"There was a lot of concern that having a recommendation not to do something would mean that doctors couldn't talk about it with their patients," she said. "Clearly, that's not true ... This absolutely in no way precludes a discussion."

Dr. Marcello Tonelli, chair of the Canadian Task Force on Preventive Health Care, agreed that men concerned about their risk of developing prostate cancer should discuss the potential benefits and harms of PSA testing with their physicians.

Tonelli said the Canadian task force last issued guidelines on PSA screening in 1994, but they "are quite consistent with these new recommendations from the United States."

The issue with PSA testing is the same as that for routine mammography for breast cancer, he said from Edmonton.

"People are afraid of getting cancer, understandably. Everyone in society has been thinking about catching it early and having a better outcome for these serious diseases, and screening has a lot of intuitive appeal — 'If we go looking for it, we'll catch it early, we'll prevent it and we'll have better outcomes as a result.'

"The trouble is in real life it's rarely that simple. The tests that we have are imperfect. They lead to treatment for people who don't need to be treated and the treatments we have are imperfect as well. Even when they remove a cancer they can cause harm."

While the Canadian task force is not working on an updated recommendation, the issue is on its radar, Tonelli said. "If there's a lot of push-back and we think it would be helpful for us to write one for Canadians, then we'll do that."

Note to readers: This is a corrected story. A previous version incorrectly said the rate of harms were 10-70/1,000

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