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Standard definition of ‘overdiagnosis’ could improve cancer screening decisions

Authors of a paper published in Annals of Internal Medicine proposed a standard definition of “overdiagnosis” regarding cancer screening to improve practices for estimating overdiagnosis and communicating potential harm to patients.

“The toll of inadequate health care is well-substantiated, but recognition is mounting that ‘too much’ is also possible,” Louise Davies, MD, MS, from the Geisel School of Medicine at Dartmouth and Dartmouth Institute for Health Policy and Clinical Practice, and colleagues wrote. “Overdiagnosis represents one harm of too much medicine, but the concept can be confusing: It is often conflated with related harms (such as overtreatment, misclassification, false-positive results, and overdetection) and is difficult to measure because it cannot be directly observed.”

In their paper, Davies and colleagues advocated for the use of a standard definition of overdiagnosis. They argued that overdiagnosis is a health threat because it exposes patients to the risks of unnecessary cancer treatment, including psychological and financial harms, without any benefits.

Davies and colleagues defined overdiagnosis as “the detection of a (histologically confirmed) cancer through screening that would not otherwise have been diagnosed in a person’s lifetime had screening not been done.”

The definition should be used to help health care providers and researchers calculate risks and communicate with patients about screening decisions, according to the authors.

The authors noted that estimates of overdiagnosis of cancer can vary greatly. They recommended that when estimating overdiagnosis, physicians should consider the uncertainties about future life expectancy. They also recommend that studies on the effects of cancer screening state their design and estimation approaches for overdiagnosis.

“Although overdiagnosis in cancer detection and screening has received public attention, current data suggest that people remain highly interested in being screened despite recognizing that a detected cancer may be indolent,” Davies and colleagues wrote. “Fear of cancer is responsible for some of these opinions; however, the problem is broader than that: Recent work to understand the U.S. public’s view of low-value care — a concept related to overdiagnosis — showed that ‘most of the healthy respondents had difficulty envisioning how health care, particularly testing, could be harmful.’”

To overcome barriers to communication and encourage appropriate decisions, the authors recommended that physicians limit numerical information, word the message in terms of outcomes and describe both benefits and harms of screening. – by Alaina Tedesco

Disclosure: Davies reports receiving funding from AHRQ. Please see study for all other authors’ relevant financial disclosures.