title: Age-Period-Cohort Analysis of Thyroid Cancer Incidence in Korea.
abstract: OBJECTIVE
  South Korea has the highest incidence rate of thyroid cancer in the world, and the incidence rate continues to increase. The aim of this study was to determine the age-period-cohort effects on the incidence of thyroid cancer in Korea.
  
  
  METHODS
  Using the Korean National Cancer registry database, age-standardized incidence rates and annual percent changes (APCs) in thyroid cancer according to sex and histologic type were analyzed between 1997 and 2011. Age-period-cohort models were applied using an intrinsic estimator method according to sex.
  
  
  RESULTS
  In both men and women, the incidence of thyroid cancer showed a sharp increase from 1997 through 2011. Among the histologic types, papillary carcinoma showed the greatest increase, with APCs of 25.1% (95% confidence interval [CI], 22.7% to 27.5%) in men and 23.7% (95% CI, 21.9% to 25.5%) in women, whereas anaplastic carcinoma did not show a significant increase in either sex. An increase in overall thyroid cancer incidence over time was observed in all birth cohorts. An age-period-cohort model indicated a steeply increasing period effect, which increased prominently from 1997 to 2011 in both men and women. The age effect showed an inverted U-shaped trend. The cohort effect tended to show a slight increase or remain constant from 1952 to 1977, followed by a decrease.
  
  
  CONCLUSIONS
  The period effect can explain the sharp increase in thyroid cancer incidence, strongly suggesting the role of thyroid screening.
authors: The Korea Central Cancer Registry, National Cancer Center, Goyang, Korea.
authors: Chang-Mo
authors: CM
authors: Oh
authors: The Korea Central Cancer Registry, National Cancer Center, Goyang, Korea.
authors: Kyu-Won
authors: KW
authors: Jung
authors: The Korea Central Cancer Registry, National Cancer Center, Goyang, Korea.
authors: Young-Joo
authors: YJ
authors: Won
authors: The Korea Central Cancer Registry, National Cancer Center, Goyang, Korea.|Molecular Epidemiology Branch, Research Institute, National Cancer Center, Goyang, Korea.
authors: Aesun
authors: A
authors: Shin
authors: The Korea Central Cancer Registry, National Cancer Center, Goyang, Korea.
authors: Hyun-Joo
authors: HJ
authors: Kong
authors: The Korea Central Cancer Registry, National Cancer Center, Goyang, Korea.
authors: Jin-Soo
authors: JS
authors: Lee
keywords: Incidence; Korea; Neoplasms; Thyroid; Time trends