Assessment of expression of novel immunohistochemical marker programmed death ligand 1(pd-l1) and its correlation with clinicopathological parameters in breast carcinoma

Abstract

INTRODUCTION: Breast carcinoma (BC) is the leading cause of tumor burden, with an incidence of 11.8%. It will cross more than 20 lakhs by the year 2030. The incidence of breast carcinoma in India has increased by more than half in the last three decades. The PD-1/PD-L1 pathway represents an adaptive immune resistance mechanism that tumor cells exert. Despite numerous studies, there is a lack of literature on such studies in Indian patients. Moreover, the results obtained from these studies have not been uniform. Recent updates in the treatment modality of breast carcinoma indicate that the use of anti-PD-L1 monotherapy will help treat advanced breast carcinoma. As PD-L1 is a newly identified marker, studies are required to understand its immunoexpression and correlation with hormone receptor status and other prognostic factors, which helps in the therapeutic management of patients. Hence, this study evaluated the expression of PD-L1 in breast carcinoma. OBJECTIVES: 1. Evaluate the immunohistochemical expression of PD-L1 marker on carcinoma Breast. 2. To analyze the correlation between the expression of the PD-L1 marker with ER, PR, HER2/neu receptors, and with various clinicopathological factors, including Age of the patient, tumor size, histologic type, histologic grade, lymph node status and pTNM staging. MATERIAL AND METHODS: Study design: Hospital-based cross-sectional study. Study Setting: The study will be held in the Histopathology section of the Department of Pathology, BLDE (Deemed to be University). Shri B.M Patil Medical College, Hospital, and Research Center, Vijayapura Study population: All breast specimens were received in the Pathology BLDE department (Deemed to be University), Shri B. M. Patil Medical College, Hospital and Research Centre, Vijayapura. Study period: 1st May 2023 to 31st December 2024. Sample size: Using G*Power ver. 3.1.9.4 software for sample size calculation, the proportion of malignant breast carcinoma tumor cells staining for PD-L1 is 14.7%; the study would require a sample size of 50 subjects with 95% confidence level and 10% absolute precision. Data collection method: All breast specimens received in the Department of Pathology diagnosed with breast carcinoma will be studied from 1st May 2023 to 31st December 2024. The tissue will be preserved in 10% buffered formalin and processed. Two sections will be prepared from each tissue block. For histopathological diagnosis, one tissue section will be stained by hematoxylin and eosin stain. Another tissue section will be mounted on poly L lysine-coated slide from paraffin-embedded tissue blocks, subjected to PD-L1 (programmed death ligand 1) immunohistochemical staining. The patient who has undergone the IHC study of estrogen, progesterone and Her-2-Neu receptors will be taken for the study. RESULTS: PD-L1 expression was seen in 14 out of 50 cases (28.0%). Expression of PD-L1 showed a statistically significant correlation with HER2/Neu. The expression of PD-L1 is not statistically significant with clinicopathological parameters such as histologic grade, TNM staging, and ER/PR expression. Hence, it cannot be used as a prognostic tumor size and grade marker. It can be helpful to assess the indication for the use of anti-PD-L1 inhibitors in advanced breast disease. Standardizing immunohistochemical (IHC) reporting for PD-L1 ensures reproducibility and reliability in evaluating breast carcinoma. Consistent and accurate PD-L1 assessment could significantly impact the application of novel targeted immunotherapies in treating breast carcinoma.