Immunohistochemical Expression of Programmed Death Ligand 1 in Squamous Cell Carcinoma of Head and Neck

Abstract

Background: Head and neck squamous cell carcinoma (HNSCC) represents one of the most prevalent  malignancies originating from the squamous cells of the nasal cavity, lip, paranasal sinuses, oral cavity, pharynx, larynx, and salivary glands.

Objectives: To assess the immunohistochemical expression and clinicopathological features of Programmed Death Ligand 1 in head and neck squamous cell carcinoma (HNSCC).

Materials and Methods: This cross-sectional study was conducted at the Department of Histopathology, Rehman Medical Institute, Peshawar, from September 2023 to December 2024. Patients of either gender with histologically confirmed head and neck squamous cell carcinoma were included in the study.  Formalin fixed tissue blocks were subjected to immunohistochemical staining with PD-L1 antibody, followed by analysis. The demographic characteristics and histopathological parameters were recorded.

Result: Among 92 participants, we observed a male predominance, with a male to female ratio of 3.8:1, and a median (IQR) age of 59.62 (56.85-62) years. PD-L1 positivity was observed in 84 patients (91.3%). The most common site of the tumor was the oral cavity in 56 (60.9%) patients followed by the larynx in 28 (30.4%) and hypopharynx in 8 patients (8.7%). We observed that lymphovascular and perineural invasion was not significantly associated with PD-L1 positivity. The T-stage of the tumors revealed that most tumors had T1 stage followed by T2 stage, while N-staging revealed most specimens 39 (46.4%) had N1 stage, followed by N0, N3, and N2 stages with a significant correlation to PD-L1 positivity. Tumors with extranodal extension and moderate tumor-infiltrating lymphocytes histologically revealed PD-L1 expression in 30 (35.7%) and 59 (70.2%) with p-1.000 and p-0.255respectively.

Conclusions: We conclude that there is a predominance of PD-L1 positivity in HNSCC with a significant correlation between PD-L1 positivity and nodal metastasis. The findings suggest that PD-L1 may have a crucial role in the biology and progression of disease. Consequently, these findings may lead to the development of immunotherapeutic strategies and aid in identification of patients who may benefit from PD-L1 targeted therapies.

Keywords: Immunohistochemistry; PD-L1; Squamous Cell Carcinoma of Head and Neck; Immunotherapy