Immunohistochemical Evaluation of PD-L1 Expression in Colonic Adenocarcinoma

Background: Colon carcinoma is one of the most common carcinomas worldwide. It is the third most diagnosed cancer and the third most common cause of cancer-related death in both men and women worldwide. PD-L1 plays major roles in physiological and pathological immune modulation, including tumor microenvironment. Aim: This study aimed to evaluate the immunohistochemical expression of PD-L1 in colonic adenocarcinoma, and its association with clinicopathologic prognostic factors. Materials and Methods: This analytical cross-sectional study was conducted at the department of Pathology of Suez Canal University Hospital and included 44 cases that were retrieved from the archived paraffin-embedded blocks at the department with their corresponding medical records, for immunohistochemical expression of PD-L1 and its role in prognosis. Results: PD-L1 expression was high in 64% of cases, and low in 25% of cases, while 11% of cases were negative. Tumor showed statistically significant association with grading, tumor infiltrating lymphocytes, neutrophilic infiltration, tumor budding, desmoplasia, and tumor necrosis. By following up the cases to assess prognosis of the disease and its impact on the 5-year survival rate, it was found that 54.5% of the studied group showed 5-year survival while 45.5% of patients were died. Conclusions: This study provides that PD-L1 expression is statistically associated with aggressive tumor characteristics of colonic adenocarcinoma. These findings suggest that PD-L1 expression may serve as an independent prognostic marker in colon tumors, with consideration given to the heterogeneity of the included studies. This information could be valuable in identifying patients likely to benefit from treatment with PD-1/PD-L1 blockers.