Physicians Mum About Overdiagnosis Risks, Patients Say

Laurie Barclay, MD

October 23, 2013

Clinicians may not tell most patients about the possibility of overdiagnosis and overtreatment as a result of cancer screenings, according to survey results published online October 21 in JAMA Internal Medicine.

"Cancer screening can produce benefits: finding true and treatable cancer at an early stage. However, it also can produce harms by overdiagnosis and overtreatment," write Odette Wegwarth, PhD, and Gerd Gigerenzer, PhD, from the Max Planck Institute for Human Development in Berlin, Germany. "Overdiagnosis is the detection of pseudodisease — screening-detected abnormalities that meet the pathologic definition of cancer but will never progress to cause symptoms. The consequence of overdiagnosis is overtreatment — surgery, chemotherapy, or radiation — that provides the patient no benefits, but only adverse effects."

The investigators performed a national cross-sectional online survey of 317 US men and women, aged 50 to 69 years, who had no history of cancer and who had been invited previously to undergo cancer screening by their physicians. In the survey, patients were asked whether their physicians had informed them about the risks of overdiagnosis and overtreatment, and how much overdiagnosis would be acceptable in terms of their decision to start or continue screening.

The survey showed that 17.0% of the patients reported having undergone no routine cancer screenings, 19.9% reported having 1 screening, 36.0% reported 2, and 27.1% reported 3 or more routine cancer screenings. The most common cancer screening reported by women was mammography. Among men, colonoscopy/sigmoidoscopy and prostate-specific antigen testing were the most common reported screenings.

Only 30 participants (9.5%) reported that their physicians had informed them regarding the possibility of overdiagnosis and overtreatment, even though 80% said they wanted to hear about possible harms before undergoing screening. More than half (51.2%) reported that they would not want to start a screening program that resulted in more than 1 overtreated person per 1 life saved from cancer death.

However, 58.9% reported that they would continue regular cancer screening they were currently receiving even if that screening led to 10 people being overtreated for each 1 life saved from cancer death.

"Most participants in our sample who underwent routine cancer screening reported that their physicians did not tell them about overdiagnosis and overtreatment," the study authors write. "The few who received information about overtreatment had unrealistic beliefs about the extent of that risk. The large number of uninformed patients might be explained by a large number of physicians who themselves know little about screening harms."

The investigators recommend that medical educators improve the quality of teaching about screening and that medical journal editors enforce clear reporting about overtreatment when publishing findings from studies on the efficacy of cancer screening.

In an accompanying commentary, H. Gilbert Welch, MD, MPH, from the Dartmouth Institute for Health Policy and Clinical Practice in Lebanon, New Hampshire, notes potential limitations of this survey. These include generalizability, skewing by the online survey design, difficulty in respondents understanding the numbers, and possible overweighting by the survey introduction of the harms of overdiagnosis and overtreatment.

"Other researchers should get involved and investigate how our patients can best understand the trade-offs and how we can learn what they want," Dr. Welch wrote.

"Whether it is prostate-specific antigen, mammography, or colorectal cancer screening, there is plenty of uncertainty about the magnitude of both the benefits and the harms," he continued.

"So, we will need to think in terms of giving patients plausible ranges — not single numbers — to express the benefits and harms of cancer screening."

This study was supported by the Harding Center for Risk Literacy at the Max Planck Institute for Human Development. The authors and commentator have disclosed no relevant financial relationships.

JAMA Intern Med. Published online October 21, 2013. Article abstract, Commentary extract


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