Frequency of Expression of PD-1 and PD-L1 In Head And Neck Squamous Cell Carcinoma And their Association With Nodal Metastasis: A Cross-Sectional Study

OBJECTIVE: The objective of this study was to determine the Immunohistochemical expression of PD- 1, PD-L1 and its association with nodal metastasis in head and neck squamous cell carcinoma. MATERIALS AND METHODS: A total of 66 cases were studied at Oral pathology/Histopathology, Armed forces Institute of Pathology (AFIP), Rawalpindi. The tissue sampling and processing yielded the formalin fixed, paraffin wax blocks. These blocks were cut into the thin sections (5 microns) by the microtome and then were mounted on the glass slides. This was followed by the routine H&E staining and then IHC staining (PD-1 and PD-L1) of these tissues mounted slides. For each case a definitive histological diagnosis was made. The two types of variables were analyzed. For qualitative variables frequencies and percentages were calculated whereas for quantitative variables means and standard deviations were analyzed. The Chi-square test then was applied to evaluate the significant difference and p-value of ≤0.05 was taken significant. RESULTS: This study was conducted at Histology department, Armed Forces Institute of Pathology, Rawalpindi over a period of one year from June 2019 to June 2020. It revealed male and female patients with 66.7% (44 Cases) and 33.3% (22cases) percentages respectively. The mean age was found to be 59.53 ± 13.637 (mean ± SD) and the mandible (37.9%) was the most commonly affected site. In total of 66 cases, 48 (72.7%) cases with metastasis of lymph nodes were presented. Out of 66 cases ,47 (71.2%) cases showed positive expression of PD-1 in the TILs seen among the primary tumor of the specimens, whereas, 40 (60.6%) cases showed positive PD-L1 expression in tumor cells of primary tumor.In comparison, as out of 66 cases ,48 (72.5%) cases showed lymph nodes metastasis, out of which 45 showed positive expression for PD-1 and 25 out of those 48 cases showed positive expression for PD-L1 in metastatic lymph nodes.The p-value turned to be significant for PD-1 IHC expression and PD-L1 IHC expression in the primary tumorand metastatic lymph nodes. CONCLUSION: A significant correlation was inferred among IHC expression of PD-1 and PD-L1 with lymph nodes metastasis. Accurate evaluation, analysis and precise management with aid of IHC markers results in initial and timely diagnosis and favorable treatment outcomes helping in the evaluation of disease course at preliminary diagnosis on incisional biopsies.