The GBD study, led by the Institute for Health Metrics and Evaluation (IHME) at the University of Washington, serves as a comprehensive database for assessing and analyzing the health impacts of diseases, injuries, and risk factors at both global and regional levels [17].In this study, we leveraged the GBD database to analyze the global burden and temporal trends of thyroid cancer attributable to HBMI from 1990 to 2021, disaggregated by year, age group, region, and economic level.

The SDI is a composite measure used to assess the development status of a country or region, derived from data on per capita income, average educational attainment, and fertility rates. It ranges from 0 to 1, with higher values indicating greater levels of societal development [18]. Our findings reveal a distinct regional disparity in the burden of thyroid cancer attributable to metabolic risk factors, with higher SDI regions experiencing a significantly greater burden compared to lower SDI regions. Specifically, the burden has increased sharply in low, middle, and low-middle SDI regions, while showing a declining trend in high and high-middle SDI regions.These findings underscore substantial differences in thyroid cancer-related DALYs and ASDR across regions with varying levels of socioeconomic development. The observed decline in thyroid cancer mortality in high SDI regions is promising and likely reflects progress in early detection and timely treatment, underscoring the effectiveness of advanced healthcare systems and cancer control strategies in more developed areas. Conversely, the persistently rising mortality rates in low SDI regions emphasize the urgent need to improve access to high-quality healthcare and implement robust cancer control programs in these underserved areas [19].

Kitahara’s study found that greater height and excess adiposity throughout adulthood are associated with higher incidence of most major types of thyroid cancer. When reducing the global adult BMI distribution to below 25 kg/m² could prevent approximately 8–14% of thyroid cancer cases worldwide. In this study, the burden of thyroid cancer attributable to HBMI was found to be associated with advancing age, with the highest burden observed in older age groups. The disease burden among females consistently exceeded that of males across all age groups, aligning with prior studies indicating that the incidence of thyroid cancer in women is approximately four times higher than in men [20]. Our age-specific analysis revealed that the global thyroid cancer DALYs and ASDR were highest among individuals aged 85 years and older, generally increasing with age.

Compared to 1990, we observed a decline in ASDR among women aged 50–84 years by 2021, while ASDR increased in all other age groups. Research suggests that estrogen may promote the initiation, proliferation, and metastatic potential of thyroid cancer cells [21,22,23,24]. After the age of 50, most women transition into perimenopause, accompanied by a gradual decline in estrogen levels, which may explain the observed reduction in ASDR among women in this age group. These age-specific trends provide valuable insights for developing targeted screening and prevention strategies tailored to different demographic groups.

HBMI induces insulin resistance, elevates levels of thyroid-stimulating hormone, and triggers the expression of various inflammatory and adipogenic factors. It can also lead to hyperglycemia and hyperlipidemia, all of which are closely linked to the development of thyroid cancer [25]. Chronic obesity-induced insulin resistance significantly increases insulin levels in the body, which may stimulate the expression of vascular endothelial growth factor (VEGF) and promote the proliferation of vascular endothelial cells in tumors. Hyperinsulinemia further enhances the expression of insulin-like growth factor 1 (IGF-1). On one hand, IGF-1 promotes cell proliferation and inhibits apoptosis, directly contributing to the initiation and progression of tumors [26]. On the other hand, it activates intracellular protein kinase B, inducing the TSH-stimulated IGF-1 receptor/mTOR signaling pathway, which promotes cell proliferation and suppresses programmed cell death [27]. Chronic inflammation increases the secretion of pro-inflammatory factors such as tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-8 (IL-8). These factors activate relevant pathways, enhancing the synthesis and secretion of chemokines, which play a critical role in the malignant transformation and progression of thyroid cells [28]. Adipokines, including leptin, adiponectin, and resistin, influence metabolism and are associated with the development and progression of thyroid cancer [29]. Implementation of WHO ‘Best-Buys’ policies—including sugar taxes, front-of-package food labeling, and restrictions on marketing of unhealthy foods to children—could lead to a population-wide BMI reduction of 0.5–1.0 kg/m² over a decade, with an associated 3–6% decrease in thyroid cancer incidence.

This GBD-based study utilizes the latest data to analyze the global burden of thyroid cancer, including mortality rates and DALYs, while assessing the contribution of HBMI and predicting future trends. However, there are several limitations to our study that should be considered when interpreting the results.

First, there is significant variation in data quality across different countries and regions. Many lower-income countries lack robust population-based cancer registries, which may lead to an underestimation of the thyroid cancer burden in these areas.

Second, our projections for the future burden of thyroid cancer are based on current data, and it is important to account for potential confounding factors and changes over time. Regular tracking and updates are necessary.Third, our study relies heavily on the methodological framework of the GBD study, which may introduce potential biases in data collection and modeling methods.Despite these limitations, our study provides valuable insights into the estimated burden and trends of thyroid cancer attributable to metabolic risk factors, laying a foundation for future research and policy development on thyroid cancer prevention and control.