The Expression of Programmed Death Ligand-1 within Stages of Oral Squamous Cell Carcinoma: Immunohistochemical Analysis

Background: Oral squamous cell carcinoma is prevalent in South Asian countries with rising cases of its incidence and mortality. Despite advancements in treatment, survival and recurrence rates are poor. Immunotherapy is a novel therapeutic modality in immunooncology. Immune checkpoint proteins are under investigation for clinical implications amongst which Programmed Death Ligand-1 has shown valuable results in certain malignancies.

Aims: To determine the immunohistochemical expression of Programmed Death Ligand-1(PD-L1) in oral squamous cell carcinoma and to find an association of Programmed Death Ligand-1 with stage and clinicopathological parameters of oral squamous cell carcinoma.

Study Design: Cross-sectional study.

Place and Duration of Study: Ziauddin Medical University, Karachi, 1 Year duration during 2018-2019.

Methods: A total number of 140 biopsy confirmed cases of oral squamous cell carcinoma were recruited in the study. Immunohistochemical expression of Programmed Death Ligand-1 was evaluated and associated with the clinicopathological parameters of oral squamous cell carcinoma (OSCC). The data was statistically analyzed through Descriptive statistics and Chi square test by using SPSS v.20.

Results: Out of 140 participants, 74% were males (n=103) and 26% were females (n=37). Programmed Death Ligand-1 positivity was observed in 62.1% of cases (n=87). The Mean age of the participants was 48.91 ± 11.7 years. The most common site of cancer involvement was buccal mucosa and majority of participants were habitual of consuming chewable products i.e. Pan, Gutka and betel nut (89; 64%). Stage III and IV tumours comprised a major portion of cases in our study. (52; 37%), (56; 40%). A statistically significant p-value was noted for the association of Programmed Death Ligand-1 with stage II and IV tumours. (P-values: 0.029, 0.001)The association of Programmed Death Ligand-1 with other variables such as age, gender, ethnicity, sites or habits was not statistically significant.

Conclusion: This study concludes that the statistical significance of Programmed Death Ligand-1 expression with tumour stage is suggestive of worsening prognosis and might have detrimental effects as tumour progresses in advanced stage. Programmed Death Ligand-1 positivity in patients having oral squamous cell carcinoma could be useful in future research in the light of cancer immunotherapy which has shown success in oncology.