One of these is the ability of microbes to modulate the host immune system, thus helping cancer cells to escape immune surveillance14 and creating the so-called pre-metastatic niche, a permissive milieu for primary cancer cell engraftment into secondary organ.15–17 Another important contribution of gut microbiota to metastasis is the promotion of angiogenesis through stimulation of vascular endothelial growth factor (VEGF) expression by lipopolysaccharide (LPS) and Toll-like receptor-4 (TLR-4).18,19. This evidence concerns the gene TLR4 and cancer.