CD8A and cancer: Tumour microenvironments are infiltrated with the immune cell types, that is, T lymphocytes cells, CD8+ T cells,101, 102 tumour‐associated macrophages,103 cancer‐associated fibroblasts, epithelial cells and cancer stem cells,104, 105, 106, 107, 108, 109 but the types of immune responses and their effects on tumour growth, metastasis and death vary greatly between different cancers and individual tumours.110