CD274 and transitional cell carcinoma: Despite these limitations, we believe that this study was the first related to PD-1(rs2227981) and PD-L1(rs2890658) polymorphisms and urothelial cell carcinoma conducted among the Japanese population and therefore may be beneficial in understanding the relationship and interactions between PD-1 and PD-L1 polymorphisms with urothelial cell carcinoma.