Programmed Cell Death-Ligand 1 Expression Status in Urothelial Carcinoma According to Clinical and Pathological Factors: A Multi-Institutional Retrospective Study

Purpose: To investigate programmed cell death-ligand 1 (PD-L1) expression status and the clinical and pathological factors related to its expression in urothelial carcinoma (UC) patients. Materials and Methods: Data from 761 UC patients who underwent testing for PD-L1 expression using the VENTANA (SP-142 immunohistochemistry assay) for measuring PD-L1 expression according to the manufacturer's protocol between February 2016 and July 2019 were retrospectively reviewed. Patients were categorized into three groups based on the percentage of tumor area covered by PD-L1-expressing tumor-infiltrating immune cells (ICs) as follows: IC0 (<1%), IC1 (≥1% and