CTLA4 and cancer: Table 5 shows the top 20 co-occurrence keywords of PCa immunotherapy with the highest frequencies. The top 20 co-occurrence keywords were composed mainly of the terms “dendritic cell”, “vaccines”, and “cancer vaccine” related to tumor vaccine and the terms “PD-L1”, “immune checkpoint inhibitors”, and “CTLA-4” related to ICI. Meanwhile, author keywords network visualization is shown in Figure 7A, conducted by VOSviewer.