Tumor Microenvironmental Interactions of Mast Cells and Lymphocytes in Gastric Cancer: A Tissue-Based Study

Background: Mast cells and tumor-infiltrating lymphocytes (TILs) are key immune components in the tumor microenvironment (TME). Their densities and interaction dynamics may influence gastric cancer progression. This research intends to investigate the density and prevalence of mast cells and CD8+ tumor-infiltrating lymphocytes in gastric adenocarcinoma while evaluating their correlation with tumor grades. Methods: This cross-sectional observational study was conducted in the Department of Pathology, Satkhira Medical College, from August 2024 to July 2025. Ethical clearance was obtained from the Ethical Review Committee of Satkhira Medical College prior to study initiation. A total of 50 cases of invasive gastric adenocarcinoma were included. Routine Hematoxylin and Eosin (H&E) staining was performed for grading. Mast cell density was assessed using toluidine blue staining and CD8+ TILs by immunohistochemistry. Associations with tumor grades were evaluated using the Chi-square test. Result: Mast cell density significantly increased with higher tumor grades (p<0.05). CD8+ TILs, both intra- and peri-tumoral, also showed a statistically significant synergistic higher distribution across tumor grades (p=0.031 and p=0.012, respectively), with higher TIL infiltration in higher grades. Conclusion: Mast cells and CD8+ lymphocytes are similarly distributed across gastric cancer grades, suggesting their synergistic roles in tumor progression. These findings highlight potential immunoregulatory cross-talk within the TME that may influence therapeutic targeting.