Senior author Dr. James Goodwin, director of the University of Texas Medical Branch at Galveston's Sealy Center on Aging, said many primary care doctors are still administering the prostate-specific antigen test to even their oldest patients despite the fact that no medical organization recommends prostate cancer screening for men older than 75.
Goodwin and colleagues found a high variability in standard PSA-ordering practice among primary care physicians. Some doctors ordered the test for their older male patients regularly, despite more than a decade of recommendations against doing so.
The doctors' tendency to order the test had little to do with measurable patient characteristics, Goodwin said.
"Our results suggest that a major reason for the continued high PSA rate is decision-making by the physicians," Goodwin said in a statement. "That's why there was so much variation among physicians, after accounting for differences among patients. It is clear that some of the overuse is because of preferences of individual patients, but the conclusion of our results is that much more is coming from their primary care physicians."
The researchers analyzed the complete Medicare Part A and Part B data for 1,963 Texas physicians who had at least 20 men age 75 or older as patients and who saw a man three or more times in 2009.
Of the 61,351 patient records examined, 41 percent of men received a PSA screening that year, and 29 percent received a screening ordered by their primary care physician.
"Overtesting can create harms, including overdiagnosis," lead author Dr. Elizabeth Jaramillo said. "The vast majority of prostate cancers are so slow growing that an elderly man is much more likely to die of another condition in his lifetime than from the cancer."
The findings were published in a research letter in the Journal of the American Medical Association.