Characteristics of Gastrointestinal Stromal Tumors incidentally discovered during abdominal surgery

Gastrointestinal Stromal Tumors (GISTs) are rare sarcomas with 5000 new cases arising in the United States each year. Despite their low incidence, general surgeons should be familiar with GISTs since a quarter of these neoplasms are encountered incidentally.

A retrospective medical records review was conducted to create a database of all GISTs resected from January 2005 to May 2019. We isolated patients who had incidental discovery of GISTs intraoperatively or within final pathology. Characteristics of patient (Age, gender), index procedure (malignant vs. benign, elective vs. emergent) and tumor (location, size and mitotic rate) were analyzed.

A total 48 patients were incidentally discovered to have a GIST excised during index operation. The mean age of these patients was 62 years, with 27 females and 21 males. The primary location of tumors in descending frequency was stomach (30), small bowel (15), colon/rectum (2) and esophagus (1). The average size of all tumors was 1.2 cm, with the average size of the stomach, small bowel, colon/rectum and esophagus at 0.9 cm, 1.7 cm, 0.9 cm and 0.3 cm respectively. Mitotic rate was less than 5 mitosis per 50 HPF in 96% of patients. Incidental tumors were identified during both bariatric (13) and non-bariatric stomach surgery (8), colorectal surgery (14), hernia repair (4), ampullary/pancreatic surgery (5), esophageal surgery (2) liver surgery (1) and uterine surgery (1). Most incidental-GISTs were identified during elective surgery (81%, 39). Finally, 15 of the tumors were identified during surgery for other malignancies.

One quarter (25%) of the GISTs encountered at our academic community cancer center over a 15-year period were discovered incidentally. These tumors had less malignant characteristics overall and were likely cured with surgical resection.