Racial/ethnic disparities and geographic clustering in pediatric thyroid cancer incidence in the United States, 1999–2022, with forecasts to 2027

BACKGROUND: The burden of pediatric and adolescent thyroid cancer is increasing. This research aimed to study the long-term incidence trends among United States (U.S.) individuals aged 0-19 years from 1999 to 2022, assess heterogeneity by sex, age, race/ethnicity, and state, evaluate COVID-19 pandemic-associated changes, and forecast incidence through 2027 METHODS: This population-based longitudinal ecological analysis used the U.S. Cancer Statistics Incidence Database queried via Centers for Disease Control and Prevention (CDC) Wide-ranging Online Data for Epidemiologic Research (WONDER). Cases were defined using ICD-O-3 site code C73.9. Age-adjusted incidence rates per 100,000 were calculated by demographic strata. Joinpoint-type segmented regression and Poisson regression were used to assess temporal trends and estimate annual percent change and incidence rate ratios (IRR). State-level geographic variation was assessed using mapped age-adjusted rates and global spatial autocorrelation (Moran's I). Forecasts (2023-2027) were generated using Autoregressive Integrated Moving Average (ARIMA) model, Exponential Smoothing State Space (ETS) model, and Poisson regression. RESULTS: From 1999-2022, 17,538 pediatric thyroid cancer cases were diagnosed. Incidence increased steeply with age, peaking at ages 15-19 (crude rate 2.58/100,000). Females had higher incidence than males (age-adjusted 1.4 vs 0.3/100,000). Rates were highest among White (1.0/100,000) and Asian/Pacific Islander (0.9/100,000) children and lowest among Black/African American children (0.3/100,000). Significant spatial clustering was observed (Moran's I=0.39, p < 0.001), with higher rates in Northeastern states and lower rates in the South. A marked decline occurred in 2020, consistent with disrupted diagnosis during the COVID-19 pandemic. Poisson models indicated a sustained upward temporal trend (IRR≈1.032 per year, p < 0.001). Forecasts suggested continued increases through 2027 (≈17% rise over 5 years; ≈37% over 10 years). CONCLUSIONS: Pediatric and adolescent thyroid cancer incidence rose steadily in the U.S. from 1999 to 2022, with pronounced socio-demographic heterogeneity and a notable diagnostic disruption in 2020. Continued surveillance and investigation of etiologic drivers and diagnostic intensity are mandatory, alongside efforts to reduce inequities in access to evaluation and care.