RNAscope and IHC confirmed that bacteria-positive regions of tissue had significant increases in CD11b+ and CD66b+ myeloid cells, along with lower densities of CD4+ and CD8+ T cells, as compared to immediately adjacent bacteria-negative regions; this indicates that the effect of the tumour-associated microbiota is highly localized (Extended Data Fig. 3c,d). This evidence concerns the gene CEACAM8 and neoplasm.