It is now well accepted that the microbes that live upon and within us play a considerable role in our body’s physiology. Evidence is also emerging that our microbiome influences the development of disease, either through protection provided by our commensal microbial community, or through changes in microbial diversity that shifts the balance towards pathogenesis. In cancer, rapidly emerging evidence suggests that the microbiome influences disease progression in a myriad of direct and indirect ways.

In this listicle, we explore key research developments including:

• The tumor–host–microbiome “system”
• The gut microbiome and bowel cancer
• Microbiome-based liquid biopsies
• The microbiome and efficacy of chemotherapy and immunotherapy