Overdetection Explains Increased Prevalence of Thyroid Cancer
Despite reports to the contrary, the prevalence of differentiated thyroid cancer is not increasing.
Despite reports to the contrary, the prevalence of differentiated thyroid cancer is not increasing, according to an article published in the Journal of Clinical Oncology.1
Previous papers indicate increasing incidence of thyroid cancer, particularly in South Korea, where there was a 15-fold increase between 1993 and 2011.2 Researchers reviewed data from 35 studies conducted between 1949 and 2007; data from 12,834 autopsies were included.
Whole or partial gland examination was the best predictor of thyroid cancer prevalence, which was not consistent over the evaluated time period. The authors attribute much of the increased incidence to overdetection, and suggest that true prevalence has remained stable.
Thyroid cancer mortality, furthermore, has remained almost perfectly stable for the past 30 years. As both detection and treatments have improved, the authors suggest that incidence of cancer is not the best explanation of current data.
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It is recommended that clinicians who detect thyroid cancers unlikely to affect a patient's life hold back treatment. If overdetection is a function of improved technology, further tests should indicate the cancers unlikely to produce systems.
- Furuya-Kanamori L, Bell KJ, Clark J, Glasziou P, Doi SA. Prevalence of differentiated thyroid cancer in autopsy studies over six decades: a meta-analysis. J Clin Oncol. 2016 Sep 6. doi: 10.1200/JCO.2016.67.7419 [Epub ahead of print]
- Ahn HS, Kim HJ, Welch HG. Korea's thyroid-cancer "epidemic"--screening and overdiagnosis. N Engl J Med. 2014 Nov 6;371(19):1765-7. doi: 10.1056/NEJMp1409841