Trends Analysis of Characteristics of Thyroid Cancer Patients in One Medical Center

BACKGROUNDThe incidence of thyroid cancer is rapidly increasing. The aim of this study is to examine time trends in the characteristics of thyroid cancer and to determine the cause of the increase of thyroid cancer. METHODS: We evaluated 4,646 patients that underwent surgery at the Asan Medical Center for thyroid cancer between 1995 and 2006. Patients were evaluated concerning the histology, size of the primary tumor, sex, and age at the time of surgery. RESULTS: Surgically treated case of thyroid cancer increased from 91 in 1995 to 960 in 2006-a 10.5-fold increase during the 12-year period. Based on the histological categories, the proportion of papillary thyroid carcinomas (PTCs) increased from 79.1% to 94.5% during the 12-year period. According to the primary tumor size in the PTCs, the proportion of PTCs measuring 1 cm or smaller increased from 14% to 56% during the 12-year period. Whereas the proportion of PTCs measuring from 1 cm to 2 cm were similar (between 31% and 41% during the 12-year period), the proportion of PTC measuring from 2 cm to 4 cm decreased from 51% to 11% during the 12-year period. Thyroid cancer affected women more often than men by a ratio of 3.7. PTC was most common in patients in their forties, especially among women. CONCLUSIONS: The increasing number of surgically treated cases of thyroid cancer is predominantly due to an increase of papillary thyroid cancer measuring 1 cm or less. These trends suggest that the increase in surgically treated cases of thyroid cancer reflects increased detection of occult thyroid cancer due to advances in medical surveillance of impalpable nodules rather than a true increase in the number of thyroid cancers.