Thyroid cancer incidence attributable to overdiagnosis in the United States 1981-2011

Papillary thyroid cancer incidence has increased in the United States from 1978 through 2011 for both men and women of all ages and races. Overdiagnosis is partially responsible for this trend, although its magnitude is uncertain. This study examines papillary thyroid cancer incidence according to stage at diagnosis and estimates the proportion of newly diagnosed tumors that are attributable to overdiagnosis. We analyzed stage specific trends in papillary thyroid cancer incidence, 1981-2011, using the Surveillance, Epidemiology and End Results national cancer registries. Yearly changes in early and late-stage thyroid cancer incidence were calculated. We estimate that the proportion of incident papillary thyroid cancers attributable to overdiagnosis in 2011 was 5.5 and 45.5% in men ages 20-49 and 50+ and 41.1 and 60.1% in women ages 20-49 and 50+, respectively. Overdiagnosis has resulted in an additional 82,000 incident papillary thyroid cancers that likely would never have caused any clinical symptoms. The detection of early-stage papillary thyroid cancer outpaced that of late-stage disease from 1981 through 2011, in part due to overdiagnosis. Further studies into the prevention, risk stratification and optimal treatment of papillary thyroid cancer are warranted in response to these trends.