PDCD1 and cancer: Compared with conventional therapy, anti-PD-1/PD-L1 monotherapies prolonged the overall survival of patients with PD-L1 expression ≥1%, but not those with PD-L1 expression <1%, regardless of cancer type; anti-PD-1/PD-L1 combination therapies reduced the risk of death in different cancer types, regardless of PD-L1 expression.