CD8A and head and neck squamous cell carcinoma: There are several possible explanations for this contradiction: (1) small sample size, (2) HPV− HNSCC represents a group of tumours that require further classification and (3) compared with the total CD8+ TILs, the PD-1+CD8+ TILs may more accurately represent the tumour-specific subset and be of greater value to prognosis and immunotherapy.31,32