PDCD1 and head and neck cancer: A high level of activated T cells and an increased abundance of dendritic cells predicted a better prognosis in cutaneous melanoma.[25] PD-1-expressing T Cells act as a biomarker predicting infusive prognosis in HPV-associated head and neck cancer.[26] Therefore, CXCL2 may play a significant role in tumor immune escape, and CXCL2 may act as a potential biomarker for immunotherapy and drug screening in STAD.