Gastrointestinal Stromal Tumors (Gist) Of The Duodenum: A French Sarcoma Group (Fsg) Retrospective Review Of 90 Patients (Pts).

10053 Background: Duodenal GIST (D-GIST) represents ≤ 5% of all GISTs, and clinicopathologic data are reported only from small series. We conducted a retrospective analysis of duodenal GIST over the past 17 years. Methods: Pts with D-GIST were identified either via survey from 19 FSG centers (71 pts) or as those enrolled in the BFR14 GIST trial (19 pts). Results: Pts were: 47 females, 43 males, with a median age of 57 years (30-84), and median ECOG 0 (0-3). Abdominal pain, anemia, and GI bleeding were the most common symptoms. Tumors (T) were localized (n=71) or metastatic (n=19), mainly D2 (30%), or D3/D4 (29%), with a median size of 6 cm (1.5-31). 78 pts had primary T resected; surgical procedures included local resection (LR) [segmental duodenectomy (n=23), wedge local resection (n=24), local excision (n=5)], and duodenopancreatectomy (DP, n=14). Resections were R0/R1 in 66 pts. T characteristics included: KIT+ (n=75), mitoses/50 HPF ≤ 5 (n= 48), or > 5 (n=20), necrosis (n=28), spindle cell (n=58). Mutations were documented in 22/29 cases, usually in KIT exon 11 (76%). 8 pts received neoadjuvant imatinib (IM) therapy (Rx) resulting in 4 PR, 3 SD, 1 PD. 10 pts received adjuvant IM Rx. With a median FU of 36 months (1-168), 78 pts (87%) are alive. 25/71 pts with localized T relapsed : 4 locally and 24 with metastases. The 4-year OS rates were 89% and 72% for localized and metastatic T. For localized T, the 4-years EFS rate was 58%. Univariate analysis showed that: age and ECOG PS have an impact on OS (p= 0.003, p <0.001), necrosis, spindle-cell type, T size, mitoses/50 HPF are predictive of relapse (p< 0.001). In multivariate analysis only mitoses/ 50 HPF predicted relapse (p< 0.001). Conclusions: Pts with completely resected primary D-GIST may have a reasonably favorable prognosis. LR rather than DP should be pursued if possible to preserve optimal pancreas function. Neoadjuvant IM should be considered to render LR feasible in pts with locally advanced D-GIST.