Background: During the past 25 years, the incidence of thyroid papillary carcinoma (TPC), especially the micropapillary subtype, has been increasing in different countries worldwide. The rise in the rate of thyroid malignancies were also determined in Turkey in the last two decades. This fact was attributed to the Chernobyl accident because Turkey is one of the affected countries by the radioactive fallout. The aim of this study was to assess the changes in the parameters of the thyroid and put forth the reasons in a 14-year period. Methods: The patient records, demographic and malignancy characteristics, and operations of 1,585 patients who had a thyroidectomy from 1996 to 2009 were reviewed retrospectively. The study was divided in two equal time periods for comparison of data. Results: A total of 216 thyroid carcinomas (13.6%) were diagnosed in the study period. There was a significant increase in the frequency of papillary (P <0.023) and micropapillary (P <0.001) carcinomas when the two different time periods were compared. The rate of follicular, medullary and other types of malignancies did not change. In the second period (2003 to 2009) of analysis, the rate of micropapillary carcinoma (P = 0.001) and within male (P = 0.031) and female (P <0.001) genders, application of total thyroidectomy (p = 0.029), and multicentric disease (P = 0.015) increased significantly. A slight decrease in the mean age of the whole number of patients and patients with papillary and micropapillary carcinomas (P >0.05) was observed. The increased number of TPC > 10 mm was insignificant. Geographic region and age specific malignancy increase was not determined. Conclusions: Micropapillary carcinoma has become a dominant type of thyroid malignancy in Turkey. The main reasons of this transition were mandatory iodization and much higher application of total thyroidectomy in surgery. Improvement in healthcare and diagnostic techniques are the complementary factors. Due to its lack of molecular and genetic basis from the perspective of thyroid cancer, the Chernobyl disaster has lost its importance in Turkey.
