Clinicopathological and mutational factors related to survival in patients with gastrointestinal stromal tumors in the American British Cowdray Medical Center in Mexico City.

Abstract

852 Background: Gastrointestinal stromal tumors (GIST) account for approximately 0.1–3% of all gastrointestinal neoplasms. In Mexico, research on GIST remains limited, and the existing studies often lack comprehensive analysis of clinicopathological features, mutational profiles, or survival outcomes. Methods: We conducted a retrospective analysis involving patients with GIST, confirmed by pathology, who were older than 18 years, at any clinical stage, and had received any form of treatment at the American British Cowdray Medical Center, a private tertiary care facility in Mexico City. Clinicopathological and mutational factors were assessed, and their association with overall survival (OS), recurrence-free survival (RFS), and progression-free survival (PFS) was analyzed. Results: Over a 20-year period (2004–2024), 84 patients were included. The cohort was mainly male (54.1%, n = 46), with a median age of 57.6 years (IQR 46.5–68.5). Most had ECOG 0 (32.9%, n = 28) and presented with abdominal pain (22.4%, n = 19). The stomach was the most frequent tumor site (49.4%, n = 42), with a median size of 7 cm (IQR 4.2–12.0). Over half showed a low mitotic rate (54.7%, n = 35). Stages were: I (20.0%, n = 17), II (9.4%, n = 8), III (14.1%, n = 12), IV (15.3%, n = 13), unknown (41.2%, n = 35). Molecular testing was performed in 16.5% of patients, revealing KIT exon 11 mutations in five cases, a PDGFRA exon 18 mutation in one case, and SDH deficiency in one case. Among localized/locally advanced cases (n = 43), 84.3% underwent curative surgery, while all metastatic cases (n = 14) received systemic therapy. With a median follow-up of 10.1 months (IQR 1.0-45.0), five patients (9.8%) died. The median OS for the entire cohort was 137.2 months (IQR 114.3–160.1). Among patients who underwent curative surgery, nine (10.6%) experienced recurrence, with a median RFS of 13.3 months (IQR 15.1–30.3). In those diagnosed with advanced disease, nine (10.6%) developed disease progression, with a median PFS of 28.8 months (IQR 9.3–17.3). Factors associated with better OS included good functional status (ECOG 0, p < 0.001) and a low mitotic index ( < 25 per 50 high-power fields, p < 0.001). Improved RFS and PFS were significantly associated with the absence of tumor rupture (p < 0.001) and a low mitotic rate (p = 0.037), respectively. No significant associations were observed with molecular factors. Conclusions: We describe one of the largest series of GIST patients reported in Mexico. Factors associated with improved OS included good functional status and a low mitotic index. The molecular testing remains underutilized. These findings underscore the unmet need for a national registry dedicated to GIST patients.