INTRODUCTION: Gastrointestinal stromal tumors (GIST) have a wide biological spectrum, ranging from benign to malignant lesions, which are prone to wide spread and frequent visceral metastasis. Currently, the prognosis is based on a score system known as risk level. However, this system has some drawbacks. For instance, tumors classified as low or intermediate risk may be associated with the development of metastasis. Therefore, studies are required to improve this classification system and incorporate recent developments such as cellular proliferation index, which has shown prognostic value in the prediction of tumor aggressiveness. OBJECTIVES: To analyze morphological criteria (macroscopic size, tumor topography, mitotic index, necrosis, histological subtype), observe risk and investigate the usefulness of immunohistochemical markers (muscle-specific actin, S-100 protein, Ki67 and p16ink4a) as prognostic markers of GIST. RESULTS: Univariate analysis showed that a reduced global survival was significantly associated with tumor size greater than 5cm, mitotic index greater than 5/50 CGA, presence of necrosis, a high risk level, and a cellular proliferation index (Ki67) higher than 5% on the reduction of overall survivel of patients (p = 0.017, 0.010, 0.001, 0.016 and 0.0005, respectively). Other factors such as histological subtype, immunophenotype and p16ink4a were not significant. CONCLUSION: According to our data, risk level, tumor size, mitotic index and the presence of necrosis stood as morphological predictors of reduced survival, which underpins previous evidence of their application. The cellular proliferation marker Ki67 associated with risk level also proved to be a useful predictor of tumor aggressiveness.
Gastrointestinal stromal tumor; Morphology; Immunohistochemical; Prognostic
