GASTROINTESTINAL STROMAL TUMOR: OUTCOMES OF THE PAST DECADE IN A REFERENCE INSTITUTION IN SOUTHERN BRAZIL

ABSTRACT - BACKGROUND: Gastrointestinal stromal tumor (GIST) is the most common mesenchymal neoplasm of the digestive tract and has a wide variation in biological behavior; surgical resection remains the main form of treatment. AIM: This study aimed to analyze clinicopathological characteristics and survival of patients with GIST in a reference institution for oncological diseases. METHODS: An observational, longitudinal, and retrospective study of patients diagnosed with GIST from January 2011 to January 2020 was carried out by analyzing epidemiological and clinical variables, staging, surgical resection, recurrence, use of imatinib, and curves of overall survival (OS) and disease-free survival (DFS). RESULTS: A total of 38 patients were included. The majority (58%) of patients were males and the median age was 62 years. The primary organs that were affected by this tumor were stomach (63%) and small intestine (17%). Notably, 24% of patients had metastatic disease at diagnosis; 76% of patients received surgical treatment and 13% received neoadjuvant treatment; and 47% of patients received imatinib as adjuvant or palliative therapy. Tumor recurrence was 13%, being more common in the liver. The 5-year OS was 72.5% and DFS was 47.1%. The operated ones had better OS (87.1% vs. 18.5%) and DFS (57.1% vs. 14.3%) in 5 years. Tumor size ≥5 cm had no difference in OS at 5 years, but DFS was 24.6%, when compared with 92.3% of smaller tumors. Patients who were undergoing neoadjuvant therapy and/or using imatinib did not show any significant differences. CONCLUSIONS: Surgical treatment with adequate margins allows the best gain in survival, and the use of imatinib in more advanced cases has prognostic equity with less advanced-stage tumors. Treatment of metastatic tumors seems promising, requiring further studies.