Correlation between PD-L1 and Ki-67 Expression at various T-stage Clear Cell Renal Cell Carcinomas

Renal cell carcinoma (RCC) is a malignant neoplasm originating from renal epithelium, with the clear cell renal cell carcinoma (ccRCC)being the most common type (80%) and the most common cause of death among other types of kidney cancer. Pathological stage is an important parameter that affects ccRCC survival, followed by nuclear grade. Pathological staging of RCC according to the AJCC (American Joint Committee on Cancer) TNM system 8th edition is based on local extension of the main tumor (T), involvement of lymph node (N), and metastasis (M). Ki-67 is a marker of proliferation used to assess tumor grade. High Ki-67 correlates with poor prognosis, advanced clinical and pathological features, thus Ki-67 can be used as a biomarker in the management of RCC.Ki-67 is routinely used to see the proliferation index in various cases of malignancy, but not in kidney malignancy. Programmed death ligand 1 (PD-L1) acts as a negative regulator of T cell-mediated anti-tumor immune responses. PD-L1 is expressed on T cells, B cells, macrophages, dendritic cells, endothelial cells and in various tumor cells including ccRCC. This study aims to determine the correlation between the expression of PD-L1 and Ki-67 in various T-stage clear cell renal cell carcinomas. Material and Method: This was an observational analytical study with cross-sectional approach toward 52 cases of ccRCC whose diagnosis was made histopathologically at the Anatomical Pathology Installation of Dr. Soetomo General Academic Hospital Surabaya from January 2014 to December 2020. Immunohistochemical stainingwas carried out using Ki-67 and PD-L1 antibodies, followed by an assessment using a scoring system. T-stage data were obtained from the patients’ medical recordswhich were then analyzed statistically with the Spearman test. Result: The study included 52 cases of ccRCC obtained from nephrectomy specimens at RSUD dr. Soetomo between 2014–2020. The age distribution of the subjects was 29–69 years and the mean and median age was 53 years. The ratio of male patients compared to female patients was 2.5:1. The majority was stage T2 (50%). Statistical test results showed no correlation between the expression of PD-L1 and Ki-67 in various T-stage clear cell renal cell carcinomas (p=0.965 and p=0.680). Conclusion: This study showed no correlation between the expression of PD-L1 and Ki-67 in various T-stage clear cell renal cell carcinomas. Nonetheless PD-L1 can be considered as an important biomarker with a poore