CD8A and exocrine pancreatic carcinoma: For example, studies in pancreatic carcinoma and head and neck squamous cell carcinoma (HNSCC) have shown the association between improved prognosis and proximity of specific cell types, e.g., CD8+ cells adjacent to cancer cells, and between the number of CD8+ cells next to a PD-L1+ or Treg cell, respectively [26, 16].