Unraveling the nexus: Tumor-Infiltrating Lymphocytes (TILs), tumor stage and PD-L1 expression in colorectal carcinoma

Abstract Background & objectives Colorectal carcinoma is one of the most prevalent causes of cancer-related mortality across the globe.Tumor-infiltrating lymphocytes have dual action in CRC, promoting anti-tumor immunity but potentially being suppressed by immune evasion mechanisms. One such mechanism is PD-L1 expression, which inhibits T-cell function and facilitates tumor progression. This study explores the relationship between TILs, PD-L1 expression, and tumor stage in CRC. Methods Cross-sectional study was conducted from July-December 2024 and included patients that were diagnosed with colorectal carcinoma and underwent surgery. A total of 70 colorectal tissue samples were examined. Patients having complete clinical data and have available archived FFPE blocks were included in our study. Quantitative data were analyzed using SPSS v.25 to find descriptive statistics and relation between different variables. Results Among the 70 cases, 67.1% were male, and 32.9% were female, with a mean age of 52.20 ± 15.2 years. The common tumor stage was T3 (61.4%), and adenocarcinoma was the predominant histological type (71.4%). TIL levels were high in 32.9%, moderate in 45.7%, and low in 21.4% of cases. PD-L1 expression was positive in 62.5%. TIL levels showed no significant association with tumor stage ( p = 0.55), whereas PD-L1 expression was significantly associated ( p = 0.04). Correlation analysis revealed a positive relationship between PD-L1 expression and tumor stage ( p = 0.033). Conclusion Study shows that TIL levels varied among cases, and their association with tumor stage was not statistically significant while PD-L1 expression increases with tumor stage, and this relation was also statistically significant suggesting its role in immune evasion and CRC progression.