Thyroid cancer is the most common cancer in women, based on the data from population-based cancer registries, South Korea.

Similar to worldwide trends, the incidence of thyroid cancer in South Korea has increased steadily in recent decades. We examined the trends in thyroid cancer incidence in Gwangju and Jeonnam provinces between 1996 and 2010, and identified 19 881 cases (men 3282/16.5%; women 16 599/83.5%) from the Gwangju Cancer Registry and Jeonnam Cancer Registry databases, which are population-based cancer registries. Age-standardized incidence rates per 100 000 persons, using hypothetical world standard population (Segi), increased from 1.9 in 1996 to 27.0 in 2010 in men, and from 10.6 to 111.3 in women, respectively. The estimated annual percentage changes (95% confidence interval) of age-standardized incidence rates were 27.1% (24.6-29.6) and 19.7% (16.4-23.2) for men and women, respectively, during the same period. The proportion of papillary-type thyroid cancer increased from 74.2 and 75.4% in 1996 to 97.9 and 98.3% in 2010 for men and women, respectively. We found the most prominent increasing trends and the highest incidence rate of thyroid cancer among those that have ever been reported. Thyroid cancer has been the leading cancer in women since 2003 and is now the fifth most common cancer in men in Gwangju and Jeonnam, South Korea.