Clinicopathological features and outcomes of patients with gastrointestinal stromal tumor at Instituto Nacional de Enfermedades Neoplásicas - Peru.

Abstract

e23523 Background: Gastrointestinal Stromal Tumors (GIST) constitute 1-2% of primary gastrointestinal cancers. The incidence is less common in the Hispanic population. Our aim was to describe the clinicopathological features and outcomes of GIST patients at a National Cancer Center in Perú. Methods: A retrospective cohort study was conducted on patients diagnosed with GIST at the Instituto Nacional de Enfermedades Neoplásicas from 2010 to 2020. Descriptive statistics and Kaplan-Meier curves were used to analyze clinicopathologic features, disease-free survival (DFS), and overall survival (OS). Results: 40 patients were included (72.5% female, mean age 55.9 years). Gastric tumors were 62.5%, jejunum/ileum 20% and duodenum 10%. The most common symptoms were abdominal pain (62.5%), abdominal mass (25%), and GI bleeding (20%). Most patients had ECOG scores of 0-1 (82.5%). Pathology showed 65% fusiform, 17.5% epithelioid, and 15% mixed tumors, with 45% being high grade. 25% of tumors were < 5cm, 30%: 5-10cm, and 42.5%: > 10cm. Additionally, 45.9% had ≥5 mitoses/50HPF. The majority of the patients were diagnosed at stage IIIB (gastric 28.0% and intestinal 66.7%), and 52.5% were classified as high risk. 90% GISTs were considered resectable and all of these underwent surgery. Adjuvant imatinib was administered to 14 patients (35%), 71.4% were high risk and 21.4% were moderate risk. 13 had complete response (92.9%) and one had disease progression (7.1%). Among these, 92.9% achieved a complete response, and one patient had disease progression. At 5 years, DFS and OS for those receiving imatinib were 74.1% and 82.5%, respectively, while for those without imatinib, DFS and OS were 74% and 72%, respectively. Recurrence occurred in 10 patients (25%); one had surgery for hepatic recurrence. Five patients (12.5%) recieved imatinib as a first-line treatment, one showed partial response, 2 had stable disease, 1 showed progression, and 1 was lost to follow-up. At a median follow-up of 57 months, the 5-year DFS and OS rates were 76% and 75%, with median DFS and OS of 101 and 106 months, respectively. Conclusions: GISTs in Peru present at more advanced stages compared to developed countries. Despite surgery and imatinib availability, overall survival rates are poorer. Policies for early diagnosis are urgently needed.