Prognosis of Gastrointestinal Stromal Tumors Arising in the Stomach and Small Intestine: A Retrospective Study of 126 Cases from a Single Institution

Seok, Sang Hee; Kim, Jun Mo; Bae, Jung Min; Kim, Se Won; Kim, Sang Woon; Song, Sun Kyo; Bae, Young Kyung

Abstract

BACKGROUND: Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor in the gastrointestinal tract. As all GISTs have the potential for aggressive clinical behavior, the guidelines for defining the risk of aggressive behavior have been developed and they have been recently revised to precisely assess these patients' prognosis. METHODS: We analyzed 94 gastric and 32 small intestinal GISTs to compare the patients' survival with the risk stratification (original and revised). RESULTS: For gastric GISTs, 10 mitoses/50HPF was an important cutoff value for the risk of metastasis (1.3% vs 29.4%, respectively), whereas 16.7% of all the small intestinal GISTs with less than 5 mitoses/50HPF metastasized. The small intestinal GISTs showed higher frequencies of mucosal invasion and coagulation necrosis than did the gastric ones. Gastric GISTs had a significantly lower incidence of metastasis/recurrence than did the small intestinal ones in the same risk group. On multivariate analysis, the anatomic location (small intestine), the tumor size (>10 cm) and the mitotic count (>10/50HPF) were independent prognostic factors for a shorter disease-free survival for patients with GISTs. The mitotic count was more important than tumor size for both gastric and small intestinal GISTs. CONCLUSION: Small intestinal GIST is a more aggressive tumor than gastric GIST and the mitotic count is the most important prognostic factor for GISTs.