[Multivariate analysis of prognosis in gastrointestinal stromal tumor].

OBJECTIVE: To identify prognostic factors in patients with gastrointestinal stromal tumors (GIST). METHODS: Hematoxylin and eosin (H&E) stained histopathological slides of tumors from patients with mesenchymal neoplasms growing in the gastrointestinal tract and abdomen were reviewed. Two histologically representative areas were identified and chosen for tissue microarray. Immunohistochemical staining was performed to demonstrate c-kit protein (CD117), CD34, smooth muscle actin, desmin and S-100 protein. The relations of various clinicopathologic features to outcome were analyzed. RESULTS: The overall disease-specific survival of 194 patients was 93.5% at 1 year, 72.1% at 3 years and 63.2% at 5 years. Univariate analysis indicated that the tumor size, mitotic count, primary location, necrosis, high cellularity, mucosal invasion, mixed cell type, hemorrhage, direct tumor invasion of surrounding tissue, male sex, incompleteness of resection, cytologic atypia were significant predictors of survival. Multivariate analysis showed that tumor size, mitotic count, necrosis, direct tumor invasion of surrounding tissue and male sex were poor prognostic signs. CONCLUSION: Tumor size and mitotic count are important prognostic factors. However, to evaluate the prognosis of these tumors, a surgical pathologist should incorporate multiple parameters into their histologic evaluation in attempt to reach an appropriate opinion on the aggressiveness of GIST.