Outcomes After Surgical Resection Differ by Primary Tumor Location for Metastatic Gastrointestinal Stromal Tumors (GISTs): a Propensity Score Matching Population Study.

PURPOSE: Primary tumor location has been identified as an important prognostic factor among patients with gastrointestinal stromal tumors (GISTs). The purpose of this study is to identify how primary tumor location may affect outcomes after resection for patients with metastatic GISTs.

METHODS: Patients with GISTs and distant metastases at diagnosis were identified in the Surveillance Epidemiology and End Results (SEER) database. Patients that underwent surgery were matched to patients that did not undergo surgery using propensity score matching (PSM) analysis.

RESULTS: After PSM, 570 patients were identified (males 334 [58.6%], females 236 [41.4%], age 62 ± 13.9 years). Gastric tumors constituted the majority (325 [57%]), followed by small intestinal (136 [23.9%]), colorectal (19 [3.3%]), and retroperitoneal/peritoneal tumors (23 [4%]). Median follow-up was 25.5 months (95% CI 23-29 months). Undergoing surgery was associated with improved disease-specific survival (DSS) on both univariate (median not reached vs. 51 months, p < 0.001) and multivariate analyses (HR 4.98, 95% CI 2.23-11.12, p < 0.001). A sub-analysis of patients with gastric GISTs showed that undergoing surgery was the only significant factor associated with improved DSS (median not reached vs. 39 months, p < 0.001, HR 2.95, 95% CI 1.92-4.53). In contrast, undergoing surgery was not associated with improved survival for small intestinal, colorectal, or retroperitoneal/peritoneal tumors.

CONCLUSIONS: Surgery for gastric metastatic GISTs is associated with improved survival. No discernible benefit after surgical resection was identified for patients with small intestinal, colorectal, retroperitoneal, or peritoneal metastatic GISTs.