Mechanistically, a circuit of bile acid, CXCL16, CXCR6, and NKT cell links gut microbes to hepatic anti-tumor surveillance: microbial 7α-dehydroxylation of bile acids lowers sinusoidal CXCL16, reduces CXCR6+ NKT cell accumulation, and favors hepatocarcinogenesis. Here, CXCR6 is linked to neoplasm.