PDCD1 and cancer: According to the guidelines of PRISMA, 22 clinical trials reporting peripheral edema events associated with PD-1/PD-L1 inhibitors, involving 15,233 cancer patients, were enrolled for the final analysis.[11,13–21,23–26,30–42] Through the data on the basic characteristics of those clinical trials (Table 1), it could be found that the incidence rate of peripheral edema was not high, but it was an universal phenomenon.