Delving deeper into the problem of overdiagnosis in medicine

Over the summer, two family physician colleagues and I published a commentary in Public Health Reviews on the implications of overscreening for carotid artery stenosis, prediabetes, and thyroid cancer. A theme connecting these three abnormalities (I won't call them "diseases," as evidence suggests that the most persons who receive these diagnoses through screening would be better off not knowing and being spared premature, costly, and/or invasive therapies) is that they are largely creations of modern medicine. A person can't feel a narrowing in a carotid artery, a slightly higher than normal blood sugar level, or a tiny thyroid nodule - instead, they learn about them after a doctor performs a test, either specifically to look for the abnormality or as an incidental finding. If the diagnosis leads to improved health outcomes, that's good news; if it only causes anxiety and unnecessary interventions, that's overdiagnosis.

2018 has seen the publication of several excellent reviews of the effects of overdiagnosis in primary care. In the Annals of Internal Medicine, Evidence-based Practice Center researchers affiliated with the U.S. Preventive Services Task Force (USPSTF) wrote about defining, estimating, and communicating overdiagnosis in cancer screening. They observed that several different study designs and approaches have been used to estimate the percentages of cancer cases that are overdiagnosed, all with limitations. (Sidebar: in a commentary in JAMA Internal Medicine, former USPSTF member Mark Ebell, MD, MS and I explored how these methods were used to produce varying estimates of overdiagnosis in randomized trials of lung cancer screening with low-dose CT scans.)

Members of the Canadian Task Force on Preventive Health Care (the evidence-based prevention panel after which the USPSTF was modeled) reviewed "causes and consequences" of overdiagnosis in primary care in a case-based discussion in Canadian Family Physician. Across the pond, the BMJ published a state-of-the-art review by two U.S. internists. Drs. Minal Kale and Deborah Korenstein pointed out that drivers of overdiagnosis include broadening disease definitions, advanced technology, public health screening programs, culture around medicine and health (e.g., "more screening is always better"), system factors (e.g., profit-driven testing, direct-to-consumer advertising, industry influence on guidelines and medical education), and limitations in evidence application. Finally, the World Organization of Family Doctors (WONCA) Europe released a position paper that defined overdiagnosis as "transforming people into patients unnecessarily" and urged family physicians, on behalf of their patients, to "demand balanced evidence informed and non emotional information material from providers and authorities in relation to cancer screening, health checks, etc."

Potential solutions to the problem of overdiagnosis should address each of the drivers, as outlined in a 2017 BMJ article by researchers at Bond University in Australia, which will co-host next year's international Preventing Overdiagnosis conference. One cancer-specific solution is to re-name low risk conditions currently labelled as cancer, such as small papillary thyroid cancers, ductal carcinoma in situ (DCIS), localized low-grade prostate cancer, melanoma in situ, and certain small lung and kidney cancers.