Clinical implications of C-kit gene mutation in patients with large gastrointestinal stromal tumors.

ABSTRACT

BACKGROUND AND AIM: To evaluate the clinical implications of C-kit gene mutation in patients with gastrointestinal stromal tumors (GIST) greater than 10 cm in size. METHODS: All cases of pathologically diagnosed GIST with positive CD117 immunostaining from one hospital were retrospectively reviewed. Tissue from the 25 patients with tumors greater than 10 cm in diameter were collected and DNA was extracted. Exons 9, 11, and 13 of the C-kit gene were analyzed and the mutations compared with the clinical and pathological characteristics of the corresponding tumors. RESULTS: Of the 25 tumors studied, 16 had C-kit gene mutations and nine did not. Of the 16 with mutations, there were four with exon 9 mutations, 12 with exon 11 mutations, and none with exon 13 mutations. Gene mutations were more frequent in male than female patients (12/13, 92% vs 4/12, 33%). There were no significant differences in age, resectability, recurrence rate, tumor characteristics (ulceration, necrosis, hemorrhage and mitotic counts), or survival in patients with or without gene mutations. CONCLUSIONS: C-kit gene mutations were frequently found in patients with large GIST, more commonly in men than in women. However, the presence of a mutation was not predictive of prognosis in patients with large GIST.