an unexpected finding of gastrointestinal stromal tumors during laparoscopic sleeve gastrectomy; how to deal? how much safety margin needed?

Background: there is an increasing incidence of coincidental gastric gastrointestinal stromal tumors (gist) during a laparoscopic sleeve gastrectomy (lsg). resection with negative margin r0 is the safest and most proper treatment. objectives: the incidence of gist in patients undergoing lsg and resection with a 1 to 2cm safety margin was validated and analyzed. the primary endpoint is that can simultaneous excision be oncologically adequate or not? how much gist is supposed to be far from a staple line?methods: the present prospective study included 338 patients with body mass index (bmi) ≥ 35. all patients underwent lsg without known history or imaging reveal gist. resection was done with a safety margin of 1 to 2 cm away from the stapled margin and, then, sent for histopathology and immunohistochemically staining.results: a total of 17 patients (5%) had coincidental gist. the size was t1 in 88.2% of patients; 16 patients were staged as ia according to the american joint committee on cancer (ajcc tnm). safety margin was ≤ 1 cm for 3 patients to avoid incorporation in staple line and 14 patients (82.3%) had 2 cm safety margin. resection margin in biopsy revealed positive resection margin r1 for 2 patients, whose safety margin was only 1 cm or less. a total of 15 patients had a negative margin (r0), whose safety margin was 2 cm .conclusions: any incidental gist can be removed safely during lsg as long as it is far from the staple line with at least a 2cm safety margin and negative resection margins without changing the procedure. margins less than 1 cm are associated with adverse prognostic factors.