(P 167) DEFINING TEXTBOOK OUTCOMES FOR MINIMALLY INVASIVE SURGICAL RESECTION OF SMALL GASTROINTESTINAL STROMAL TUMORS (GIST) OF THE STOMACH

Objective: The mainstay of treatment for small gastric GIST is surgical, with the goal of a macroscopically complete resection, intact tumor capsule, and negative resection margin. Textbook Outcome (TO) represents the ideal surgical outcome and has been utilized to assess the quality of surgical care. We aimed to define and analyze TO rates for minimally invasive gastric GIST resections in a multi-institutional patient cohort.

Methods: Patients with small gastric GIST ≤ 5 cm who underwent laparoscopic/robotic resection from January 2014 to January 2024 were retrospectively identified from two GIST centers. To balance optimal oncologic and perioperative outcomes, we defined TO as R0 resection, no tumor rupture, recurrence-free at 2 years (MSKCC nomogram predicted 95% of patients), no conversion to open, no intra-/post-operative transfusions, no intraoperative complications, operative time ≤ 120 minutes, no complications ≥ Clavien-Dindo II, length of stay (LOS) ≤ 3 days, and no 90-day readmission or death. We excluded patients with concurrent procedures (e.g., cholecystectomy), incidental peritoneal disease, and tumors with adjacent organ involvement.

Results: Eighty-three patients met inclusion criteria. TO was achieved in 63.9% of cases (N=53). Mean age was 64.9 ± 10.6 years and 60.2% (N=50) of patients were female. Mean tumor size was 3.0 ± 1.0 cm and 71.1% of GIST were classified as modified-NIH low risk (i.e., mitotic index ≤5/mm2). Mean operative time was 105.2 ± 49.0 minutes. Mean LOS was 2.4 ± 1.3 days. Among non-TO, operative time >120 minutes (N=20, 24.1%) and LOS >3 days (N=15, 18.1%) were the most common disqualifying factors. One case (1.2%) was converted to open, and one case (1.2%) had an R1 resection. There were four 90-day readmissions (4.8%) and one case with staple line bleeding requiring reintervention (endoscopy), but no reoperations or perioperative deaths. At a mean follow up of 32.6 ± 24.1 months (range: 0.3–99.1), 3 patients (3.6%) had recurrences within 2 years postoperatively. With extension of the operative time standard, our TO rate increases to 74.7% (≤ 150 minutes, N=62) and 80.7% (≤ 180 minutes, N=67).

Conclusion: Minimally invasive gastric GIST resection is well described in the literature. Herein, we defined TO standards to better define what patients can expect, as well as to serve as a measure of short-term and long-term performance/outcomes for benchmarking. Further validation is needed to determine the TO criteria that best balance quality assurance and generalizability across health systems.