CD4 and head and neck squamous cell carcinoma: In research data, resting memory CD4+ T cells are often associated with prognosis of malignant tumor diseases, such as bladder cancer (43), head and neck squamous cell carcinoma (44), and colorectal cancer (45), and it is speculated that FAT3 mutations are related to the infiltration state of resting memory CD4 + T cells, activated NK cells, and resting dendritic cells in triple-negative breast cancer.