Traditional methods for detecting tumor-reactive (TR) CD8 + tumor-infiltrating lymphocytes (TILs) in pancreatic cancer usually focus on neo-antigenic epitopes, which is limited by the narrow range of antigenic epitopes, and the lengthy and complex identification processes, resulting in an incomplete understanding of the biological characteristics of TR CD8 + TILs. The gene discussed is CD8A; the disease is pancreatic neoplasm.