Originally published in MedPage Today
by Todd Neale, MedPage Today Staff Writer
Men might not be getting the information they need to make an educated decision about prostate cancer screening, two new studies suggest.
Among 375 men surveyed by telephone, only 69.9% had discussed a prostate-specific antigen (PSA) test with their physician before making a decision about screening, according to the first study, reported in the Sept. 28 issue of Archives of Internal Medicine.
Of those who did talk with their physicians about the test, nearly all (93.9%) had discussed the benefits of screening but only 32% had talked about the potential downsides, said Richard Hoffman, MD, MPH, of the New Mexico VA Health Care System and the University of New Mexico in Albuquerque, and colleagues.
Although the majority (58%) said they felt well informed to make a decision, only 47.8% were able to answer any of the three questions they were asked to determine their knowledge about prostate cancer and the test.
“Therefore, these discussions — when held — did not meet criteria for shared decision-making,” Hoffman and colleagues said.
“Our findings suggest that patients need a greater level of involvement in screening discussions and to be better informed about prostate cancer screening issues.”
In an accompanying editorial, Steven Woolf, MD, MPH, and Alex Krist, MD, MPH, of Virginia Commonwealth University in Richmond, said an initial look at the data suggests that clinicians should make more of an effort to improve shared decision-making.
Healthcare professionals “should use decision aids and other tools to help patients obtain accurate, evidence-based information about the advantages and disadvantages of testing,” they said.
Although most men older than 50 have undergone a PSA test, there is little evidence supporting the benefits of screening.
In fact, the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, conducted in the U.S., found that screening did not reduce mortality over 10 years.
The European Randomized Study of Screening for Prostate Cancer found a moderate 20% relative reduction in the risk of death; the absolute risk reduction was seven deaths per 10,000 men screened through nine years of follow-up.
But the issue has not been resolved, the researchers said, and some question whether the benefits of screening outweigh the risks. Treatment of early-stage prostate cancer — which may not eventually lead to any problems — results in impotence, incontinence, or both in about 50% of men.
“Moreover, the harms of screening begin to accrue immediately, whereas the potential benefits are realized only many years later,” said Michael Pignone, MD, MPH, of the University of North Carolina at Chapel Hill, in another editorial on the topic.
“Given the current state of knowledge, physicians, patients, and policymakers must attempt to integrate the information on benefits and downsides to reach a decision about what to do,” he concluded.
Most professional organizations advocate for a patient-physician conversation to discuss this tradeoff before undergoing a PSA test, but there has been little information about whether these discussions were taking place.
Hoffman and colleagues turned to the National Survey of Medical Decisions to find out.
The subsample of 375 men who had either undergone or discussed PSA testing with clinicians in the previous two years was included in the analysis.
Most of the men (93.1%) said they thought PSA testing reduces prostate cancer mortality.
Even though the majority felt they were well informed about the risks and benefits of screening and thought they were involved in the decision, a large minority (45.2%) said their physician had not asked them about their preference for testing.
Although the men performed poorly on questions about the test, the editorialists Woolf and Krist questioned whether the topics covered were the most relevant.
“The investigators assessed ‘knowledge’ with questions about the prevalence and mortality rates for prostate cancer,” they said, “but knowledge about the benefits, harms, and uncertainties that men should weigh before being screened would be more germane.”
Hoffman’s group acknowledged that they “addressed only a limited spectrum of prostate cancer knowledge.”
Additional limitations included potential recall bias, the lack of information on health literacy, and the inclusion of mostly white, married men with relatively high socioeconomic status.
In the second study on the subject in the Archives, Kirsten Howard, PhD, MPH, of the University of Sydney, and colleagues used statistical modeling to estimate the risks and benefits of PSA testing among men of different ages and risk levels.
They assumed a 20% relative reduction in the risk of death for those who underwent PSA testing.
The results of the models showed that the benefits and harms of screening vary with age and risk level.
For every 1,000 low-risk 60-year-olds who undergo screening, for example, there will be 53 diagnoses of prostate cancer and 3.5 cancer-related deaths per year during a 10-year period. In a similar cohort that does not undergo screening, there will 23 diagnoses and 4.4 deaths.
There will be more than twice as many complications in the screened cohort — 26 versus 12.
In addition, screening will result in a high rate of false-positives. Up to 21.1% of low-risk men who get regular PSA tests will have a false-positive within 10 years.
The patterns of diagnoses and deaths were similar in high-risk men, because they have more prostate cancer deaths as well as more diagnoses and treatment-related complications.
Overall, men who are screened are two to four times more likely to be diagnosed, but death rates — both cancer-related and overall — do not differ significantly from men who are not screened, the researchers said.
“Before undergoing PSA screening, men should be aware of the possible benefits and harms and of their chances of these benefits and harms occurring,” Howard and her colleagues wrote.
“Even under optimistic assumptions, the net mortality benefit is small,” they said. “These quantitative estimates can be used to support the goal of individual informed choices about PSA screening.”
They acknowledged some limitations of their analysis, including the use of several assumptions to account for uncertainties in the data and the use of mortality and not quality of life as the measured outcome.
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