CD8A and cancer: The immune cell microenvironment of the cancer tissue was characterized previously with immunohistochemical markers for CD3 (T lymphocytes), CD4 (T‐helper cells), CD8 (cytotoxic T cells), CD20 (B cells), CD45RO (memory T cells), CD138 (plasma cells), CD163 (M2‐like macrophages), FOXP3 (regulatory T cells), and NKp46 (NK cells) and quantified as the percentage of viable cells in the stroma and tumor compartment separately [20].