Correlation between programmed cell death ligand1 (PD-L1) expression and clinical parameters in colorectal carcinoma

Objectives: Programmed cell death ligand1 (PD-L1) tissue expression in colorectal cancer (CRC) displays conflicting results among various studies. We aimed to identify the rate of PD-L1 positivity in colorectal carcinoma, and its immune infiltrating cells, their relationship with clinicopathological parameters of patients, and to correlate the results with other studies. Methods: PD-L1 antibody retrospectively analyzed immunohistochemically in tissue microarray blocks of 99 specimens with colonic and rectal carcinomas operated between January 2015 and December 2017. A comparison performed between PD-L1 expression in tumor cells (TCs) as well as tumor-infiltrating immune cells (TIICs) for age, sex, histological differentiation, the primary tumor location, number of involved lymph nodes, angiolymphatic invasion, and TNM stage. Results: Of the 99 patients, the median age was 54.5 (range: 18-3) years. Fourteen samples were PD-L1 positive in TCs, increased to 32% in TIICs. A significant expression of PD-L1 in TCs was correlated with medullary histology (p= 0.03), number of the involved lymph nodes (p= 0.02), distant metastasis (p= 0.001), and TNM stage (p= 0.0001). The PD-L1 status in TIICs was again connected with adverse clinical and pathological parameters. Conclusions: The expression of PD-L1 in TCs and TIICs is associated significantly with advanced cancer or lymphatic invasion in patients who underwent surgery after a diagnosis of CRC. The research designates the significance of estimation of TCs and TIICs in correlation to clinicopathological characteristics of patients a finding that could produce a piece of evidence for precise electing immunotherapy.