A new Canadian guideline recommends that the prostate-specific antigen (PSA) test should not be used to screen for prostate cancer based on evidence that shows an increased risk of harm and uncertain benefits. The guideline is published in CMAJ (Canadian Medical Association Journal)
"Some people believe men should be screened for prostate cancer with the PSA test but the evidence indicates otherwise," states Dr. Neil Bell, member of the Canadian Task Force on Preventive Health Care and chair of the prostate cancer guideline working group. "These recommendations balance the possible benefits of PSA screening with the potential harms of false positives, overdiagnosis and treatment of prostate cancer."
For men with prostate cancer diagnosed through PSA screening, between 11.3% and 19.8% will receive a false-positive diagnosis, and 40% to 56% will be affected by overdiagnosis leading to invasive treatment. Treatment such as surgery can cause postoperative complications, such as infection (in 11% to 21% of men), urinary incontinence (in up to 17.8%), erectile dysfunction (23.4%) and other complications.
Prostate cancer is the most commonly diagnosed non-skin cancer in men and the third most common cause of death from cancer in men in Canada. However, the prognosis for most prostate cancers is good with a 10-year survival rate of 95%. Prostate cancer is generally slow to progress and usually not life-threatening.
The guideline, aimed at physicians, other health care professionals and policymakers, contains prostate cancer screening recommendations for using the PSA test with or without manual rectal examination of men in the general population. Based on the latest evidence and international best practices, the guideline updates the previous version published by the task force in 1994.
- For men under age 55 and over age 70, the task force recommends not using the PSA test to screen for prostate cancer. This strong recommendation is based on the lack of clear evidence that screening with the PSA test reduces mortality and on the evidence of increased risk of harm.
- For men aged 55–69 years, the task force also recommends not screening, although it recognizes that some men may place high value on the small potential reduction in the risk of death and suggests that physicians should discuss the benefits and harms with these patients.
- These recommendations apply to men considered high risk — black men and those with a family history of prostate cancer — because the evidence does not indicate that the benefits and harms of screening are different for this group.
"Any use of PSA testing to screen for prostate cancer requires a thoughtful discussion between the clinician and the patient about the balance between unclear benefits and substantial harms," states Dr. James Dickinson, member of the prostate cancer guideline working group.
The guidelines are consistent with the recommendations of the US Preventive Services Task Force and the Cancer Council Australia. The United Kingdom does not have an organized screening program but recommends that men concerned about the risk of prostate cancer receive balanced information on the benefits and harms of screening.
The task force recommendations are based on systematic evidence reviews and use an international framework for assessing quality of evidence and the strength of recommendations for clinical guidelines (GRADE).
To help patients and their physicians make informed decisions, the task force has created tools to help patients and physicians in decision-making about testing. Visit http://www.canadiantaskforce.ca.
The Canadian Task Force on Preventive Health Care has been established to develop clinical practice guidelines that support primary care providers in delivering preventive health care. The mandate of the task force is to develop and disseminate clinical practice guidelines for primary and preventive care, based on systematic analysis of scientific evidence.
"The task force's guideline is an excellent example of health care decisions being made from the perspective of evidence-based medicine," writes Dr. Murray Krahn, University Health Network and University of Toronto, Toronto, Ontario, in a related commentary. "However, it paid insufficient attention to patient values, patient preferences and costs."
"The task force's guideline provides a good summary of the data on the effectiveness of prostate cancer screening and a reasonable review of the rate at which potential harms occur," he states. However, several elements could provide more complete information for making decisions. These include a comprehensive review of patient harms, a review of modelling studies, evidence on cost as well as more on patient preference and shared decision-making, of which there is substantial literature.
Dr. Krahn suggests that recommendations for clinical practice should be based on patient preferences, social values and health care costs in addition to evidence on outcomes.
"The falling overall mortality in some countries that screen intensively [for prostate cancer], the evidence that treatment may have a very modest disease-specific mortality benefit, and the highly variable preferences for treatment outcomes suggest to me that we should not push patients out of decision-making in this area," concludes Dr. Krahn.
Canadian Medical Association Journal