A national expert panel is recommending doctors stop screening men for prostate cancer.
The Canadian Task Force on Preventive Health Care says there is no evidence that PSA screening reduces overall death from prostate cancer among men of any age, most cancers detected are slow growing and as many as 56 per cent of all men diagnosed with prostate cancer are over diagnosed — meaning the cancer never would have caused symptoms or killed the man during his lifetime.
Over diagnosis exposes men to needless treatments that can lead to impotence, incontinence and other complications of radiation or surgery, the task force warns in new guidelines to be published Monday in the Canadian Medical Association Journal.
Overall, the controversial screening tests results in only a 0.1 per cent reduction in death from prostate cancer, the task force found.
The PSA, or prostate specific antigen test, measures a protein produced by the prostate gland. The higher the man’s blood PSA levels, the more likely he is thought to have cancer. Many doctors recommend an annual PSA starting at age 50.
But even higher-than-normal PSA counts don’t necessarily mean the man has prostate cancer, and cancer can be present even with low PSA levels.
The recommendations apply to men in the general population. Those at increased risk of developing, and dying from prostate cancer include black men and men with a family history of the disease.
The task force says doctors should discuss the benefits and harms of screening higher risk men.
Symptoms of prostate cancer can include weak urinary flow, an urgent need to urinate, frequent urination during the day and especially at night and blood in the urine.
Introduced in the 1990s, the PSA test was originally meant to help monitor men diagnosed and treated for prostate cancer. But it’s use quickly spread to include screening healthy men as well.
Before the PSA test, “we didn’t really have anything, except for the digital rectal examination,” said Dr. Neil Bell, chair of the task force’s working group on prostate cancer screening and a professor in the department of family medicine at the University of Alberta.
“It was a nice blood test you could do and hopefully it would tell you that the men you were screening were at risk for prostate cancer or not,” he said. But the test was widely adopted before there was any good evidence supporting using it as a screening tool.
Most prostate cancers have a good prognosis, and the survival rate is the highest among all cancers in men. Overall, about 95 per cent of men diagnosed with prostate cancer will survive at least 10 years.
About 14 per cent of men will be diagnosed with prostate cancer at some point in their lifetime, but fewer than four per cent of men will die from the disease.
The national task force, which is funded by the Public Health Agency of Canada, “looked at the evidence for the harms and benefits of PSA screening and decided that it’s not a good thing to do,” said Bell.
Overall, the task force found that for every 1,000 men screened, 102 men will be diagnosed with prostate cancer. But 33 of these 102 prostate cancers would not have caused illness or death.
As well, five men will die from prostate cancer despite undergoing PSA screening, while one man will escape death from prostate cancer because of screening.
Overall, the task force recommends:
• In men younger than 55, and men 70 and older, the task force strongly recommends against screening with the PSA test.
• For men aged 55 to 69 — the core age group — the task force also recommends not screening. The panel says there may be a “small but uncertain” reduction in the risk of dying from prostate cancer by screening men in this age group, but there is also a high risk of false-positives, unnecessary biopsies and over diagnosis.
“There is some potential benefit, but we’re concerned about the harms,” Bell said.
The harms come in not from the blood test, but from what happens after the blood test comes back, he said.
Men who screen above a certain PSA threshold are often sent for a biopsy. A biopsy involves taking multiple samples from the prostate. “Sometimes they do six, sometimes they do 12. In some places they’ve gone up to 32 cores,” Bell said.
Minor biopsy-related complications can include bleeding and infections, but about two per cent of men end up hospitalized with major complications, and about one to two per 1,000 die within 120 days of having their biopsy, Bell said.
“If you screen positive on the biopsy, you could be a candidate for surgery, radiation or hormonal therapy.” Surgery and radiation can cause erectile dysfunction and urinary incontinence. There is also now growing concern over whether hormone therapy also increases the risk of heart disease “because it’s a fairly potent dose of drugs that are given,” Bell said.
The risk of prostate cancer increases with age. By the time men reach age 60 or 70, “well over half or more would have something in their prostate you could diagnose as cancer,” Bell said.
However, “The majority of these men will never suffer any complications or symptoms from this disease — they will die from something else before they die from prostate cancer.”
For some men, screening “comes down to your values and preferences,” Bell said. “We recommend against screening, but there may be some men who value that small benefit” of one life saved for every 1,000 men screened, “and who aren’t so worried about the harms,” he said.
The new Canadian guidelines are similar to those produced by a U.S. task force two years ago. Australia also recommends against routine PSA screening.
skirkey@postmedia.com
