Immunohistochemical expression of programmed death ligand (PD-L1) is associated with poor differentiation, higher tumor-infiltrating lymphocytes, and higher t and n stage in colorectal adenocarcinoma: A single-center analytical study of 52 cases in South India

Background Colorectal adenocarcinoma is the fourth leading cause of cancer-related mortality worldwide. These tumors are heterogeneous in terms of genomic alterations, immune response of the microenvironment, drug responsiveness, and biological behavior. Physiologically and pathologically, programmed cell death ligand 1 (PD-L1) is a key immune-regulatory molecule that suppresses immune response. PD-L1 expression on tumor cell has been implicated as a cause of immune evasion by tumor cells in many cancers. However, its activity in colorectal carcinomas is still under study. Objectives The aim of this study is to correlate PD-L1 marker expression with patient demographics, clinicopathological features, and TNM (tumor size, node involvement, and metastasis status) stage, and to find if there exists any significant correlation between them. Materials and Methods The present study is a 3-year retrospective analytical study conducted in a tertiary care hospital in South India. Specimens were routinely fixed, processed, and cut. Hematoxylin and eosin–stained sections and corresponding PD-L1-stained sections were analyzed and data were tabulated. Statistical analysis Results were tabulated and statistical analysis was done using Statistical Package for the Social Sciences (SPSS) software (version 24). The chi-squared test was used to calculate the value of significance (p value). Results PD-L1 expression on tumor cells was significantly associated with female gender, right-sided tumors, poorly differentiated tumors, higher number of tumor-infiltrating lymphocytes, and higher T and N statuses. Conclusion High PD-L1 expression on tumor cells is a marker for poor prognosis. A subset of colorectal adenocarcinoma may benefit with anti-PD-L1-targeted therapy.