In particular, CD45RO+ , indicating memory T cells, CD8+ T cells, CD20+ B cells and CD68+ macrophages have been convincingly shown to associate with prognosis in the context of other gastrointestinal malignancies (i.e. colo-rectal cancer and pancreatic adenocarcinoma) [20–24], while IL-17 (indicating Th17 T cells mostly, but also other myeloid types) and PD-1 identify cells with critical roles at mucosal sites [25–27] or in the context of immunotherapy [28–30] respectively. The gene discussed is CD8A; the disease is rectal cancer.