Continued rise in the incidence of thyroid cancer in Iran: true increase or overdiagnosis?

Abstract

Objectives: Thyroid cancer (TC) is commonly recognized as the most prevalent type of malignancy affecting the endocrine system. This study aimed to assess the incidence of TC and its trends in the Iranian population.

Methods: The incidence rate of TC in Iran was determined using data from the Iranian National Population-based Cancer Registry (INPCR). The INPCR registered all new cancer cases through various diagnostic methods, including pathology reports, clinical and paraclinical data, and death registry reports.

Results: From 2014 to 2018, a total of 27,530 cases of TC were recorded. Among these cases, 21,932 (79.7%) were female, and 5,598 (20.3%) were male. The age-standardized incidence rate (ASR) of TC was 6.17 (95% confidence interval [CI]: 6.09-6.25) per 100,000 person-years, showing an upward trend from 4.61 (95% CI: 4.45-4.77) per 100,000 population in 2014 to 8.17 (95% CI: 7.97-8.37) in 2018. The ASR of TC in women was nearly 3.7 times higher than that in men (9.79 vs. 2.59 per 100,000 person-years). The ASR of TC was highest in younger age groups among women (40-50 years) compared to men, who had higher rates in older age groups (65-75 years). Papillary thyroid carcinoma (PTC), including its follicular variant, was the predominant histological type of TC in the Iranian population, accounting for 82.19% (n = 22,627) of cases, followed by follicular thyroid carcinoma (FTC) (n = 859; 3.12%).

Conclusions: Our data suggest that thyroid cancer rate has increased in Iran though comprehending the underlying reasons for this phenomenon requires further research.