• Alejandro González-Motta, Gabriela Negrete-Tobar, Oscar A Messa-Botero, Juliana Pineda-Ortega, Isabella Garciandía, Juan S Álvarez-Martiínez, Natalia Londoño-De Vivero, and Ricardo Bruges-Maya.
• Unidad Funcional de Radioterapia, Centro de Tratamiento e Investigación sobre Cáncer, Luis Carlos Sarmiento Angulo.
• Gac Med Mex. 2024 Jan 1; 160 (4): 393398393-398.

BackgroundIn Colombia, gastric cancer is fifth in incidence (12.8 cases per 100,000) and third in mortality (9.9 cases per 100,000). Microsatellite instability (MSI), a phenotype in gastric cancer treatment, lacks comprehensive exploration in Colombian and Hispanic/Latino populations. Data scarcity hinders immunotherapy approval in middle-income countries.ObjectiveCharacterize the prevalence of MSI phenotype in Colombian patients with gastric and gastroesophageal junction cancer.Materials And MethodsWe measured MLH-1, MSH-2, MSH-6, and PMS-2 expression in tumor pathology by immunohistochemistry markers. We conducted descriptive analysis and Fisher's test to identify associations for MSI expression.ResultsFinal sample size was 106 patients, mean age of 62.5 years (25-93 ± 14.2). Prevalence of MSI was 12.26% (n = 13). We found an association between older age and positive MSI (p = 0.0042), as well as with non-diffuse histologic subtypes (p = 0.019).ConclusionPrior studies report 22% MSI phenotype prevalence in gastric tumors, mostly in developed countries, excluding Hispanic/Latino populations. Identifying the prevalence of MSI in our population as 12.26% could pave the way for approving immune blockade drugs as a treatment option for these patients in Latin American countries. Our data could be utilized to conduct cost-utility studies in support of this.Copyright: © 2024 Permanyer.

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