Attitudes on PSA hinge on how test is described
■ Three approaches to explaining the screening resulted in varying percentages of patients who identified reduced risk of prostate cancer death as its most important aspect.
By Christine S. Moyer — Posted Feb. 25, 2013
Men's preferences and values about prostate cancer screenings are influenced by the way physicians present information on the prostate-specific antigen test, according to a team of scientists led by the University of North Carolina.
Fifty-four percent of men who were asked to rate and rank PSA test attributes as part of what's known as a values clarification task said reducing the chance of prostate cancer death was the most important aspect of the screening, according to a study published online Feb. 11 in JAMA Internal Medicine, formerly Archives of Internal Medicine. In contrast, only 35% of men who examined a balance sheet and 33% who participated in a discrete choice experiment considered reduction in the chance of prostate cancer mortality to be the most important screening attribute, the data show.
Values clarification tasks aim to clarify patient preferences for various health care decisions and can be embedded in decision aids. The balance sheet task in this study featured a table of data on the potential benefits and drawbacks of PSA screening versus no screening. The other method, the discrete choice experiment, asked participants to choose among scenarios regarding prostate cancer screening.
The findings reinforce the “need for primary care physicians to talk to their patients about PSA screening decisions,” said Michael Patrick Pignone, MD, MPH, the senior study author.
“If [doctors] use a decision aid to supplement the discussion, that's a good thing to do. But don't take a one-size-fits-all approach to PSA screening,” said Dr. Pignone, a professor of medicine at University of North Carolina School of Medicine. He said more studies are needed to determine the best values clarification method for PSA screening decision making.
Prostate cancer is the second-most commonly diagnosed cancer among U.S. men and remains the second-leading cause of cancer death in men after lung cancer, according to the American Cancer Society. The organization estimates that there will be 238,590 new cases of prostate cancer diagnosed in 2013, and 29,720 will die of the disease.
Researchers for the University of North Carolina study issued online surveys about PSA testing in October 2011 to 911 men ages 50 to 70 who had no personal or family history of prostate cancer. Half of the men lived in the U.S., and the other half resided in Australia. Participants randomly were assigned to one of three values clarification methods — a balance sheet, a rating and ranking task, or a discrete choice experiment.
Researchers found there was little discrepancy among participants when asked if they intended to have a PSA test. Seventy-seven percent of men in the balance sheet and the rating and ranking groups planned to get the screen, as did 74% of men in the discrete choice experiment group.
But when presented with a description of the screening without labeling identifying it as a PSA test, only 44% of men in the balance sheet category said they preferred that screening option over no screening, the study said. Similarly, the unlabeled PSA test option was preferred by only 34% of those in the rating and ranking category and 20% in the discrete choice experiment group.
These findings might indicate “that people have attached an unwarranted positive value to the PSA test label. But when they see what it constitutes, they're not as enthusiastic about it,” Dr. Pignone said.
Exercise lessens prostate cancer risk
An unrelated study published online Feb. 11 in Cancer found that increased exercise is associated with a reduced risk of prostate cancer and high-grade prostate cancer among white men.
DID YOU KNOW:
Prostate cancer is the second-most commonly diagnosed cancer among U.S. men.
There was no association between exercise and prostate cancer risk for black men, according to the study of 307 men who were scheduled for prostate biopsies at the Veterans Affairs Medical Center in Durham, N.C., between January 2007 and June 2011. This partly could be because blacks have different genetic susceptibilities than whites that predispose them to prostate cancer, the study said.
Another possibility is that exercise is believed to impact hormonal pathways, and black men might have different hormonal profiles than white men, said lead study author Lionel L. Baņez, MD.
Researchers found that whites who exercised nine or more metabolic equivalent hours per week were 53% less likely to have positive biopsies compared with white men who exercised for fewer than three MET hours each week, the study said. Exercising at a level of three METs was considered mild activity, such as easy walking or yoga, the study said. Physical activity at a level of nine METs was described as strenuous and included running and vigorous swimming.
The findings need to be validated in larger studies before physicians should consider amending exercise recommendations for patients, Dr. Baņez said. He urges doctors to continue encouraging regular physical activity for all patients.
“Exercise is generally known to promote health and reduce risk of obesity, cardiovascular and metabolic diseases,” he said. “These are [conditions] that contribute significantly more to mortality among men than prostate cancer.”