Temporal and Geographical Trends of Incidence of Thyroid Cancer in Golestan, Iran, 2004-2013.

Background: Thyroid cancer is the most common type of endocrine cancer. We aimed to determine the incidence rates of thyroid cancer across a 10-year period (2004-2013) in Golestan, Iran. Methods: We obtained the thyroid cancer data from Golestan Population-Based Cancer Registry (GPCR). Age-standardized incidence rates (ASR) were calculated and reported per 100000 person-years. The Joinpoint software was used to assess time trends, and average annual percent changes (AAPCs) and their corresponding 95% confidence intervals (CIs) were reported. Results: Of 326 registered patients, 83 (25.5%) were men and 243 (74.5%) were women. The mean age was 51.3 and 42.6 years for males and females, respectively. Overall, the ASR of thyroid cancer was 2.2 per 100000 person-year (AAPC = 2.76; 95% CI: -3.68 to 9.64). The test of co-incidence showed a statistically significant difference in the incidence of thyroid cancer between men (1.3) and women (3.2) (P < 0.001). According to our results, the ASR of thyroid cancer in western parts of Golestan is higher, including Gorgan and Aliabad cities. Conclusion: Increasing trends in incidence rates of thyroid cancer were found in the Golestan province during the study period, especially in women. We found significantly higher rates of thyroid cancer in women. Geographical diversities were seen in incidence rates of thyroid cancer in the Golestan province. Our results may be helpful for designing further researches to investigate the epidemiological aspects of thyroid cancer in the Golestan province.