Moreover, there are several factors in the included studies which can also influence gender-specific differences in the outcome parameters and should be addressed in further research, such as reporting the results only for the intention-to-treat population, the histological and molecular subtypes of urothelial carcinoma, the PD-1/PD-L1 expression status in the studies and their immune-histochemical evaluation with different assays as well as the proportion of bladder carcinomas and UTUC in the studies. This evidence concerns the gene CD274 and urinary bladder carcinoma.