Three Decades of Gastrointestinal Stromal Tumor Incidence in the United States: Joinpoint Trend Analysis and ARIMA Forecasting Through 2032

Background: Gastrointestinal stromal tumors (GIST) are the most common mesenchymal neoplasms of the gastrointestinal tract, with incidence rising globally over the past two decades. The evolution of targeted therapies, particularly imatinib, and recent systemic disruptions such as the COVID-19 pandemic may have influenced incidence patterns at the population level. Methods: We used Surveillance, Epidemiology, and End Results (SEER) data to examine U.S. GIST cases diagnosed between 1992 and 2021. Age-adjusted incidence rates (AAIRs) were calculated per 100,000 persons standardized to the 2000 U.S. population. Temporal trends were analyzed using Joinpoint regression to identify statistically significant inflection points, and Auto-Regressive Integrated Moving Average (ARIMA) models were employed to forecast incidence through 2032. Model performance was assessed via root mean squared error (RMSE), mean absolute percentage error (MAPE), and Theil’s U statistic using a train–test split. Results: The overall mean AAIR for GIST during 1992–2021 was 0.66 per 100,000, with higher rates among Black populations (1.22) compared with White (0.55) and Asian/Pacific Islander groups (0.94). Joinpoint analysis identified two significant breakpoints: 2002, marking a deceleration in incidence growth, and late 2019, where a sharp increase emerged. The ARIMA(0,1,0) with drift model provided the best fit and forecasted AAIR exceeding 2.5 per 100,000 by 2032. Conclusions: GIST incidence in the United States has increased steadily over three decades, with clear demographic disparities and distinct temporal inflection points corresponding to therapeutic and systemic shifts. These projections signal a growing clinical and public-health burden, emphasizing the need for expanded diagnostic capacity, equitable access to molecular testing, and ongoing surveillance to monitor post-pandemic trends.