The recent recognition of the symbiotic gut microbiome (which is now estimated to have over 10 million genes) as a fundamental component of human biology has led to an explosion of interest in microbial variation in relation to the pathogenesis of non-infectious diseases, including cancers and variation in individual responses to therapy. There is growing evidence that microbiome activities are relevant to many areas of cancer research from basic mechanisms to improving and personalising treatments. This session presents three exemplar views of the microbiome universe - from the perspectives of basic microbiotal compositional and function, a cancer aetiopathogenesis and from the perspective of cancer therapy and surgery.