# Spatiotemporal Epidemiology of Female Thyroid Cancer: A Retrospective Population-Based Registry Study in the Hamadan Province, Iran (2010–2019)

## TL;DR

This study analyzed how thyroid cancer in women changed over time and space in Iran's Hamadan province from 2010 to 2019, finding rising rates and regional differences.

## Contribution

The study provides new spatiotemporal insights into female thyroid cancer trends in a specific Iranian region using advanced statistical methods.

## Key findings

- Female thyroid cancer incidence increased by 14.5% annually in Hamadan province from 2010 to 2019.
- High-risk clusters were identified in northern and central counties, while southern counties showed decreasing trends.
- A significant high-risk cluster was found in Hamadan county during 2018–2019, and a low-risk cluster in southern areas from 2010–2013.

## Abstract

Thyroid cancer (TC) incidence varies regionally in Iran, with a notable increase observed in females. However, region-specific spatiotemporal epidemiological data are limited. This study aimed to quantify the spatiotemporal trends and geographic clustering of female TC in the Hamadan province, western Iran, from 2010 to 2019.

Female TC cases from the Hamadan province were obtained from the population-based cancer registry. County-level standardized incidence ratios (SIRs) were calculated to adjust for differences in population size, and were smoothed using a hierarchical Bayesian spatial smoothing model that accounts for spatial and temporal dependence. Temporal trends were analyzed using joinpoint regression. Spatiotemporal clusters were identified using space-time scan statistics.

The incidence of female TC showed an average annual increase of 14.5% (Average annual percent change [AAPC]: 14.5, 95% confidence interval: 4.7 to 25.3; P<0.001) from 2010 to 2019 in the Hamadan province. The smoothed SIRs indicated increasing trends in northern and central counties, including Hamadan, Asadabad, Famenin, Razan, and Tuyserkan, while decreasing trends were observed in southern counties such as Nahavand and Malayer. A significant high-risk spatiotemporal cluster was identified in the Hamadan county during 2018–2019 (observed-to-expected cases ratio: 2.24, P<0.001), and a low-risk cluster was detected in Nahavand, Malayer, and Tuyserkan from 2010 to 2013 (0.51, P<0.001).

This study revealed significant spatiotemporal heterogeneity in female TC incidence in the Hamadan province. Identification of high-risk clusters provides an evidence base for targeted preventive measures and health resource allocation.