Supplementary Material for: Clinicopathological Characteristics, Surgery and Survival Outcomes of Patients with Duodenal Gastrointestinal Stromal Tumors

<i>Background:</i> Duodenal gastrointestinal stromal tumors (GISTs) are a rare subset of GISTs (3-5%), and their clinicopathological features have not been fully described. The purpose of this retrospective study was to examine these characteristics and compare the operative procedures. <i>Methods:</i> Twenty-five patients with duodenal GIST underwent complete resection, local resection (LR) or pancreaticoduodenectomy (PD) from 1990 to 2014 at our 2 hospitals. We analyzed patient characteristics, treatments, histological examinations, postoperative complications and survival outcomes. <i>Results:</i> Twelve patients (48%) with no symptoms were incidentally diagnosed for unrelated reasons. Sixteen patients (64%) had c-<i>kit</i> mutations while 6 (24%) were wild-type, including 4 with a history of neurofibromatosis type 1. Comparing LR (n = 16) and PD (n = 9), the recurrence-free survival rate was significantly worse for PD. On multivariate analysis, however, tumor size was an independent and significant prognostic factor, but not operative procedure. There was no body weight change with LR, but body weight decreased by 7% with PD.<i>Conclusion:</i> Duodenal GISTs had different characteristic genetic mutations compared to other GISTs. LR for duodenal GISTs appears to be oncologically and nutritionally feasible.