Editorials

Overdiagnosis of thyroid cancer

BMJ 2016; 355 doi: https://doi.org/10.1136/bmj.i6312 (Published 30 November 2016) Cite this as: BMJ 2016;355:i6312
  1. Louise Davies, associate professor of otolaryngology (head and neck surgery)1 2 3
  1. 1VA Outcomes Group, Department of Veterans Affairs Medical Center, White River Junction, VT, USA
  2. 2Section of Otolaryngology, Geisel School of Medicine at Dartmouth
  3. 3Dartmouth Institute for Health Policy and Clinical Practice
  1. Correspondence to: L Davies, VA Outcomes Group, 111B, 215 North Main Street, White River Junction, VT 05009, USA Louise.Davies{at}Dartmouth.edu

Non-lethal cancers picked up by screening are probably responsible

Thyroid cancer incidence has increased dramatically in many countries in the developed world over the past three decades.1 Papillary thyroid cancer, which has been responsible for virtually the entire increase, is rarely lethal. The 20 year survival rate is greater than 90%, and approaches 100% for the smallest cancers.2 The increasing incidence is most likely due to overdiagnosis—the detection of subclinical cancers never destined to cause harm.3 4 This conclusion has been reached because the incidence has been primarily due to the detection of small papillary cancers, mortality due to thyroid cancer has not changed significantly, and small foci of papillary thyroid cancer are commonly found at autopsy in people who died of other causes. Overdiagnosis is a problem because it exposes people to the potential side effects of treatment, but without an equal expectation of benefit, because the cancer is unlikely to advance.

In a linked article in The BMJ,5 Park and colleagues extend our understanding of the issue in South Korea, which has seen a 15-fold increase in incidence over the past 10 years,6 …

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