Global health inequities in thyroid cancer among adolescents and young adults from overdiagnosis to inadequate care by the socio-demographic index.

INTRODUCTION

Thyroid cancer is the most common and rapidly increasing malignancy among adolescents and young adults (AYAs, aged 15-39 years). While this trend is well-documented, a critical gap exists in understanding how the disease burden varies with socioeconomic development. This study analyzes global disparities in the AYAs thyroid cancer burden across Socio-demographic Index (SDI) levels, identifying ecological patterns that suggest the dual challenges of overdiagnosis and inadequate care.

METHODS

We explored the global disparity in disease burden of thyroid cancer among AYAs utilizing the Global Burden of Disease Study 2021. Age standardized incidence rate (ASIR), age standardized prevalence rate (ASPR), age standardized mortality rate (ASMR), and age standardized disability-adjusted life years (DALYs) rate (ASDR) were extracted for analysis. Temporal trends were assessed using Average Annual Percentage Change (AAPC), estimated through joinpoint regression analysis. To further explore the relationship between development level and disease burden, restricted cubic splines were employed to model the non-linear relationship between SDI and AAPC.

RESULTS

From 1990-2021, the global ASIR and ASPR for thyroid cancer in AYAs increased significantly (P < 0.001), with ASIR rising from 0.93 (95% UI: 0.83-1.06) to 1.59 (95% UI: 1.34-1.92) per 100,000 population. In contrast, the ASMR and ASDR remained consistently low and stable. In 2021, high SDI regions recorded the highest ASIR and ASPR, whereas low SDI regions showed the highest ASMR and ASDR. Notably, an inverse U-shaped curve was observed when exploring the correlation between SDI and the AAPC, with AAPC peaking at an SDI of approximately 0.55.

CONCLUSIONS

Socioeconomic development acts as a double-edged sword in the AYA thyroid cancer epidemic. High-SDI regions exhibit a burden pattern indicative of potential overdiagnosis, while low-SDI regions experiencing higher mortality likely reflect gaps in timely diagnosis and care capacity. The peak burden increase at a low-middle SDI of 0.55 signals a critical transition point. These findings support differentiated strategies that emphasize diagnostic appropriateness, risk stratification, and avoidance of unnecessary detection in high-SDI regions while strengthening essential treatment capacities in resource-limited settings.