Surgical Management of Adolescents and Young Adults With Gastrointestinal Stromal Tumors: A US Population-Based Analysis.

Importance: There is a dearth of population-based evidence regarding outcomes of the adolescent and young adult (AYA) population with gastrointestinal stromal tumors (GISTs). Objectives: To describe a large cohort of AYA patients with GISTs and investigate the effect of surgery on GIST-specific survival (GSS) and overall survival (OS). Design, Setting, and Participants: This retrospective cohort study of 392 AYA patients and 5373 older adult (OA) patients in the Surveillance, Epidemiology, and End Results (SEER) database with GISTs histologically diagnosed from January 1, 2001, through December 31, 2013, with follow-up through December 31, 2015, compared the baseline characteristics of AYA (13-39 years old) and OA (≥40 years old) patients and among AYA patients stratified by operative management. Kaplan-Meier estimates were used for OS analyses. Cumulative incidence functions were used for GSS analysis. The effect of surgery on survival was evaluated with a multivariable Fine-Gray regression model. Exposure: Tumor resection. Main Outcomes and Measures: GIST-specific survival and OS. Results: This study included 392 AYA and 5373 OA patients diagnosed with GISTs (207 [52.8%] male AYA patients, 2767 [51.5%] male OA patients, 277 [70.7%] white AYA patients, and 3661 [68.1%] white OA patients). Compared with the OA patients, more AYA patients had small-intestine GISTs (139 [35.5%] vs 1465 [27.3%], P = .008) and were managed operatively (332 [84.7%] vs 4212 [78.4%], P = .003). Multivariable analysis of AYA patients found that nonoperative management was associated with a more than 2-fold increased risk of death from GISTs (subdistribution hazard ratio, 2.27; 95% CI, 1.21-2.25; P = .01). On subset analysis of 349 AYA patients with tumors of the stomach and small intestine, small-intestine location was associated with improved survival (OS: 91.1% vs 77.2%, P = .01; GSS: 91.8% vs 78.0%, P = .008). On subset analysis of 91 AYA patients with metastatic disease, operative management was associated with improved survival (OS: 69.5% vs 53.7%, P = .04; GSS: 71.5% vs 56.7%, P = .03). Conclusions and Relevance: This study found that AYA patients are more likely to undergo surgical management than OA patients. Operative management is associated with improved OS and GSS in AYA patients, including those with metastatic disease.