Evaluation of Programmed Death Ligand-1 Immunohistochemical Expression and Tumor-Infiltrating Lymphocytes in Different Types of Endometrial Carcinoma

BACKGROUND: Endometrial cancer (EC) identified at an early stage is successfully treated in a majority of patients with surgery with or without radiotherapy or chemotherapy. For patients with advanced disease, however, the prognosis is poor; 5-year survival rates are less than 50% in patients with lymph node metastases and less than 20% with peritoneal or distant metastases. Previous studies proved that programmed death-1/programmed death ligand-1 (PD1-/PD-L1) blockers are currently effectively used as immunotherapies in a number of tumors such as melanoma and non-small cell lung cancer. AIM: This study was conducted to determine the expression of PD L1 in endometrial carcinoma and to assess its potential role as a biomarker for different types that can be used to screen candidates fit for immunotherapy. MATERIALS AND METHODS: This cross-sectional study was carried out on 32 cases of endometrial carcinoma cases that underwent endometrial biopsies, dilatation, and curettage or radical hysterectomies at Ain Shams University Hospitals Pathology Units from 2018 to 2020 with their clinical and radiological assessments. Correlation between hematoxylin and eosin-stained histopathological sections and PD-L1 immunohistochemical staining of the same sections, mainly emphasizing the tumor-infiltrating lymphocytes, was done. RESULTS: PDL-1-positive expression of both tumor cells and TILs was significantly more frequent in type II endometrial carcinoma (p = 0.04 and 0.03, respectively) using a cut-off value 10%, compared to type I. Moreover, Grade III tumors showed significantly more frequent PDL-1 expression in both tumor cells and TILs than Grade I and II tumors, using 5% and 10% cut-off values indicating that PDL-1 is overexpressed in aggressive tumors. CONCLUSION: PD-L1 staining is significantly related to high-grade tumors and type II endometrial carcinomas, the aggressive types, which support their probable benefit from immunotherapy. Separate assessment of PD-L1-positive staining in both tumor cells or TILs with a cut-off value 10% can significantly reflect the aggressiveness of the tumor and its probable benefit from immunotherapy.