CD8A and cancer: High numbers of Treg cells and low CD8 T cell to Treg cell ratios have been found to correlate with poor prognosis and reduced survival of patients with many types of cancer, including ovarian cancer [7, 8], lung cancer [9], pancreatic ductal adenocarcinoma [10, 11], non-Hodgkin's lymphoma [12], glioblastoma [13], melanoma, and other malignancies [14, 15].