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 2-cm 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 2-cm safety margin and negative resection margins without changing the procedure. Margins less than 1 cm are associated with adverse prognostic factors.