Changes in standardized mortality rates from thyroid cancer in Korea between 1985 and 2015: Analysis of Korean national data.

Background: The incidence of thyroid cancer has increased very rapidly in Korea; however, most previous studies suggested that the mortality rate for thyroid cancer remained stable. The objective of the current study was to evaluate recent changes in standardized thyroid cancer mortality using data from Statistics Korea.

Methods: Population and mortality data from 1985 through 2015 were obtained from Statistics Korea. Age-standardized mortality rates (ASMRs) from thyroid cancer per 100,000 population were calculated based on the World Health Organization standard population.

Results: In Korea, the ASMRs from thyroid cancer increased from 0.17 (95% confidence interval [CI], 0.17-0.18) per 100,000 in 1985 to 0.85 (95% CI, 0.83-0.86) per 100,000 in 2004, which was the highest among all countries. Subsequently, the ASMRs continuously decreased to 0.42 (95% CI, 0.41-0.43) per 100,000 between 2004 and 2015. The estimated annual percent change (APC) from 1985 to 2004 was 7.94 (95% CI, 6.43-9.46), and the corresponding value from 2004 to 2015 was -4.10 (95% CI, -5.76 to -2.40). Changes in the ASMRs reflected similar patterns in men (1985-2003: APC, 8.51; 2003-2015: APC, -4.32) and women (1985-2004: APC, 7.62; 2004-2015: APC, -4.38) and were also observed in older patients (aged ≥ 55 years).

Conclusions: Thyroid cancer mortality in Korea increased until 2004 and then continuously decreased until 2015. Increases in the early diagnosis of thyroid cancer, changes in exposure to risk factors, and standardization in diagnosis and treatment may be associated with the decrease in thyroid cancer mortality in Korea. Cancer 2017; 123:4808-14. © 2017 American Cancer Society.