CD274 and cancer: A meta-analysis collecting six studies which included 7877 cases has showed that a high expression level of PD‐L1 might lead to the mitigation of the host's anti-tumor immune response by activating of the immune checkpoint PD-1/PD‐L1 pathway, thus resulted in increased tumor aggressiveness [34] including inhibiting T-cell proliferation, promoting immune cell apoptosis, and might help these tumors evade anti-cancer immune responses.