Adjuvant systemic therapy for intermediate and large gastric gastrointestinal stromal tumors (GISTs): Is there a survival benefit following margin negative surgical resection?

Background: The value of adjuvant systemic therapy after margin-negative resection for gastric gastrointestinal stromal tumors (GISTs) remains unclear. Methods: The National Cancer Data Base was queried to identify patients undergoing margin negative resections for gastric GISTs >2 cm between 2010 and 2015. Patients were stratified by tumor size (small: 2.1–5 cm, intermediate: 5.1–10 cm, large: >10 cm), histologic grade (low: ≤5 mitoses/50 HPF and high: >5 mitoses/50 HPF), and use of adjuvant therapy. Multivariable cox proportional hazard methods were used to compare overall survival (OS). Results: 3520 patients met inclusion criteria. Adjuvant therapy was associated with a statistical improvement in OS (86% vs. 76%, p = 0.014) for those with large tumors but had no measurable effect in patients with small or intermediate sized tumors. On multivariable analysis, this association was independent of grade.