CD8A and cancer: Different lymphocyte subtypes, including cytotoxic T cells (Tc, CD8 positive), T helper cells (Th, CD4 positive), regulatory T cells (Treg, FOXP3 positive), natural killer cells (NK, CD56 and CD57 positive), and B cells (CD79a or CD20 positive), have all received attention for their importance in the prognosis of a wide range of cancers.