To study the utility of PDL1(Programmed Cell Death Ligand One) expression as a immunohistochemical marker for assessing tumor behavior in comparison to histopathological grading and TNM staging in oral squamous cell carcinoma patients.

**Aim:**To study the utility of PDL1(Programmed Cell Death Ligand One) expression as a immunohistochemical marker for assessing tumor behavior in comparison to histopathological grading and TNM staging in oral squamous cell carcinoma patients.

Objectives:

1.     To confirm already diagnosed cases of oral squamous cell carcinoma

2.     To evaluate PDL1 expression in oral squamous cell carcinoma.

3.     To compare PDL1 expression in oral squamous cell carcinoma with the grade and TNM staging of oral squamous cell carcinoma

Background :

The incidence of head & neck tumours is increasing worldwide. One of the most prevalent cancers worldwide is the oral cancer. Every year, an estimate 405,000 new cases of oral cancer are projected globally; the countries with the highest rates are Bangladesh, Bangladesh, India, Sri Lanka, Hungary, and France. It’s predicted that 66,650 new cases occur annually in the European Union. Oral cavity, salivary glands, and pharynx are all impacted by oral carcinoma. They are a major cause of death in developing nations as they are associated with serious health problems.

The three primary risk factors for carcinoma are tobacco usage, alcohol use, along with the consumption of betel nuts. Patients on immunosuppressive medication, receiving organ transplants, and those with HIV are more likely to acquire OSCC (oral squamous cell carcinoma).

OSCC is indicated by a reddish-white lesion having uneven surface but well-defined margins. Early lesions are usually painless. As they develop, some may produce nodularity, ulceration, and discomfort. One notable characteristic is presence of an ulcer that is difficult to palpate and has uneven edges. One significant development in the management of OSCC is immunotherapy with this strategy, cancer cells are directly targeted and destroyed by the immune system. Tumour and inflammatory cells express "programmed cell death ligand one" (PD-L1), which is a membrane protein. Immunohistochemistry, a method that employs the antibodies to find certain proteins in tissue samples, is used to determine its existence. The evaluation of PD-L1 expression is thought to be a critical biomarker and it is essential for the identification of individuals who might benefit from immunotherapy. The method employed to assess the expression of PD-L1 is immunohistochemistry which is used to visualise and quantify the levels of PD-L1 expression in tissue samples, antibodies specific to the protein.[3] Transmembrane protein PD-L1 is expressed on both immune cells which infiltrates the tumour and neoplastic cells, such as cancer cells. PD-L1 interacts with Programmed Cell Death Protein 1 (PD-1), that is typically expressed on activated T cells. The self or the cell in question inactivates the immune response against tumour cells as a result of this interaction. Recent research has shown that the PD-1/PD-L1 axis is commonly altered in a significant proportion of cases of squamous cell carcinoma of the oral cavity. This modification suggests that the tumour may have a vulnerability that might be exploited by therapeutic the  intervention.PDL1 expression in oral squamous cell carcinoma can be used in diagnostic evaluation of patients. Therefore, this study will be performed with the aim to know the the utility of PDL1 (Programmed Cell Death Ligand One) expression as an immunohistochemical marker for assessing tumor behavior in comparison to histopathological grading and TNM staging in oral squamous cell carcinoma patients.

Methodology*:* Samples of 94 patients who will be to the Department of General Pathology with the specimen of oral SSC will be selected after they fulfill the requirement of the criteria. The specimens will undergo the gross examination and inspection, CAP guidelines will be used to assess the tumor’s histological grading and TNM grading will be used to assess the tumor’s staging. PDL1 immunostaining will be performed in each instance to assess protein expression. The sample will further undergo the PDL1 staining and immunohistopathology.

Expected outcome*:* Significant outcomes in the PDL1 expression as immunohistochemical maker for the assessment of tumor behavior in comparison to histopathological grading & TNM staging in OSCC patients.