PDCD1 and cancer: Tumors with higher PD-L1 expression tend to have better response rates to anti-PD-1 treatments in many types of cancer, and current evidence in HNSCC suggests that combined positive score (the sum total of PD-L1–positive tumor cells, lymphocytes, and macrophages divided by the total number of tumor cells) acts as an effective evaluation to screen patients for immunotherapy (10).