The anti-tumoural immune response against CRCs is apparently closely linked to the molecular pathogenesis of these tumours, and MSI-H CRCs typically present with features of a pronounced local immune response, for example a high density of tumour-infiltrating lymphocytes with a high proportion of activated and cytotoxic CD8-positive lymphocytes (Dolcetti et al, 1999; Smyrk et al, 2001; Phillips et al, 2004; Jenkins et al, 2007). This evidence concerns the gene CD8A and neoplasm.