GIST identified during bariatric surgery: to treat or not to treat?

Background: Gastrointestinal stromal tumors (GIST) are rare GI tumors that compose 1% of GI tumors. With the rise in obesity, bariatric surgery is becoming an increasingly common procedure and the incidental GISTs in this population have been noted more often than in the general population.

Objective: We evaluated and characterized the incidental GISTs in our bariatric surgical population.

Setting: The study was completed at a Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program-accredited academic hospital system.

Methods: All GISTs identified during Roux-en-Y gastric bypass and laparoscopic sleeve gastrectomy between January 1, 2005 and December 31, 2016 were evaluated. Typical demographic, clinicopathologic, treatment, follow-up, and outcome data were recorded.

Results: Within the 2655 bariatric surgeries at our institution, 17 GISTs were identified (.64%). Mean age was 54 years; 94% of lesions were identified intraoperatively. Lesions were identified in the fundus (29.4%) or body (70.6%), were unifocal, and <1 cm; 94.1% of resections had clear margins. Histology revealed 88.2% spindle cell and 11.8% mixed histology with <5 mitoses/50 fields, portending a low malignancy potential. Follow-up included the bariatric surgeon and oncology consult; 17.6% were recommended by oncology for computed tomography surveillance. No recurrences were recorded.

Conclusion: We present the largest cohort to date of incidental GISTs in a bariatric population. A diligent intraoperative examination of the serosa in the left-behind portion of the remnant in bypass and the discarded remnant in sleeves allows the bariatric surgeon the opportunity to leave the patient cancer-free after removal of incidental tumor.