Predictors of Recurrence After Resection of Small Gastric Gastrointestinal Stromal Tumors of 5 cm or Less

Goals: To evaluate the recurrence predicting factors of small gastric gastrointestinal stromal tumors (GISTs) through the long-term follow-up after surgical/endoscopic resection. Background: Although small gastric GISTs are known to have a low risk of recurrence after complete resection, the prognostic factors are not well known. Study: The study retrospectively analyzed the records of 136 patients with primary gastric GISTs of 5 cm or less without metastasis who underwent surgical/endoscopic resection between March 1997 and December 2008 at the Asan Medical Center, and who were followed-up for at least 3 months after resection. Specimens were assessed for tumor size, mitotic index, and microscopic resection margin. Specimen sections were immunohistochemically stained to determine the levels of expression of the cell cycle proteins p53, p16(INK4), pRb, cyclin D1, and Ki-67. DNA was extracted from high-risk tumors to analyze for KIT mutations. Results: Among 136 patients, 5 (3.7%) patients with tumors with a high mitotic index showed recurrence at a median 23 months post resection. None of 14 patients with microscopic positive resection margins showed recurrence during a median follow-up time of 32 months. A high mitotic index was a predictor of recurrence (P < 0.001), but that tumor size, method of resection, or margin status were not. In addition, abnormal p53 expression was found to be associated with recurrence (P = 0.004). All assessable high-risk tumors had a KIT exon 11 mutation. Conclusions: Predictors of recurrence of gastric GISTs of 5 cm or less were a high mitotic index and abnormal p53 expression. A positive microscopic resection margin was not associated with recurrence.