K. E. Fero1, T. M. Coe5, J. D. Murphy4, J. K. Sicklick2 1University Of California – San Diego,School Of Medicine,San Diego, CA, USA 2University Of California – San Diego,Division Of Surgical Oncology And Department Of Surgery,San Diego, CA, USA 3University Of California – San Diego,Division Of Medical Oncology And Department Of Medicine,San Diego, CA, USA 4University Of California – San Diego,Radiation Medicine And Applied Sciences,San Diego, CA, USA 5Massachusetts General Hospital,Department Of Surgery,Boston, MA, USA
Introduction: There is a dearth of population-based evidence regarding outcomes of the adolescent and young adult (AYA) population with gastrointestinal stromal tumors (GIST). The aim of this study is to describe a large cohort of AYA patients with GIST and investigate the impact of surgery on GIST-specific and overall survival.
Methods: This is a retrospective cohort study of patients in the Surveillance, Epidemiology and End Results (SEER) database with histologically-diagnosed GIST from 2001-2013, with follow-up through 2015. SEER is a population-based cancer registry with 18 sites covering approximately 30% of the United States. We identified 392 AYA patients among 5,765 patients with GIST; the main exposure variable identified was tumor resection and the primary outcome measure was mortality. Baseline characteristics were compared between AYA (13-39 years old) and older adult (OA; ³40 years old) patients and among AYA patients stratified by operative management. Kaplan-Meier estimates were used for overall survival (OS) analyses. Cumulative incidence functions were used for GIST-specific survival (GSS) analyses. The impact of surgery on survival was evaluated with a multivariable Fine-Gray regression model.
Results: There was no significant difference between AYA and OA patients with regards to sex, race distribution, tumor size or stage. Compared to OA, more AYA patients had small intestine GISTs (35.5% vs 27.3%, P <0.01) and were managed operatively (84.7% vs 78.4%, P < 0.01). Multivariable analysis of AYA patients demonstrated that non-operative management was associated with over a 2-fold increased risk of death from GIST (SDHR 2.271; 95% CI:1.214-2.249). On subset analysis of AYA patients with tumors of the stomach and small intestine (n=349), small intestine location was associated with improved survival (OS: 91.1% vs 77.2%, P=0.01; GSS: 91.8% vs 78.0%, P<0.01). On subset analysis of AYA patients with metastatic disease (n=91), operative management was associated with improved survival (OS: 69.5% vs 53.7%, P=0.04; GSS: 71.5% vs 56.7%, P=0.03).
Conclusion: We report the first population-based analysis of GIST outcomes in the AYA population. These patients are more likely to undergo surgical management than patients in the OA cohort. Operative management is associated with improved overall and GIST-specific survival in AYA patients, including those with metastatic disease.
