Blog | Wednesday, October 23, 2013

QD: News Every Day--Lack of knowledge about risks of cancer overdiagnosis widespread among doctors, patients


Physicians who don’t know enough about risks of overdiagnosis for cancer screenings has led to too many patients being uninformed as well, a study concluded.

Researchers conducted an online survey of 317 U.S. men and women ages 50 to 69 years to find out how many patients had been informed of the risks of overdiagnosis and overtreatment, as well as and how much overdiagnosis they would tolerate when deciding whether to start or continue screening.

Results appeared online Oct. 21 at JAMA Internal Medicine.

Of the sample, nearly 20% reported undergoing 1 routine cancer screening, 36% reported 2 screenings, 27% reported 3 or more, and 17% indicated undergoing none. Women most commonly underwent mammography and men most often underwent colonoscopy/sigmoidoscopy and prostate-specific antigen (PSA) testing.

Of the entire sample, only 30 (9.5%) people recalled that their physician had informed them about the possibility of overdiagnosis and overtreatment. Nine of these patients indicated that their physician quantified the risk of overdiagnosis, but in 8 of those cases, patients recalled overestimates or underestimates of the risks for these screenings than the figures reported in the medical literature.

Just over half (51%) of all participants would not undergo a screening that hypothetically resulted in more than 1 overtreated person per 1 life saved from death due to cancer, while nearly 59% would continue cancer screening that they are already receiving regularly, even if they learned that the test results in 10 overtreated persons per 1 life saved from cancer death. And, 69% of the sample indicated that they would not start screening if overdiagnosis was 10 or more cases per 1 life saved, such as in mammography and PSA testing.

Researchers noted that the large number of uninformed patients might be due to the large number of physicians who know little about screening harms, pointing out that a national sample of 412 U.S. primary care physicians showed that nearly 34% of doctors could not provide a correct estimate of overdiagnosis for mammography and nearly 43% could not do so for PSA testing.

“Our results should prompt medical educators to improve the quality of teaching about screening and encourage medical journal editors to enforce clear reporting about overtreatment when publishing results on the effectiveness of cancer screening,” the authors wrote. “These means may not be sufficient but would be a first step toward enhancing the number of physicians and patients who thoroughly understand the potential consequences of taking a cancer screening test.”

An accompanying editorial used fairly frank language to drive home the point that more research is needed.

“Our patients have been taught to think differently about screening. There are no harms. It’s always good to know. It is just about gathering information. Of course you want it. It is a brain-dead decision,” the editorial states. “In reality, the truth is more nuanced. There are benefit and harms to consider in screening—just as there are in treatment. There’s no longer any argument about this. Even the American Cancer Society signs on to the idea of overdiagnosis—using the word in its materials on breast, lung, and prostate cancer screening. The arguments are, instead, about the magnitude of the benefits and harms.”