Expected results: This project is based on two related concepts. First, that lifestyle behaviours and obesity may alter gut microflora leading to changes in BA metabolism, enhancing production of specific BA known to be cancer promoting. Second, observations of increased BA levels post-VSG surgery, which may improve metabolic function, but some BA may be pro-carcinogenic over the longer term. The project will provide improved understanding of the inter-relations between BA, lifestyle behaviours and metabolic factors and the development of hepatobiliary cancers. It will also identify specific BA most strongly associated with these highly malignant cancers. The findings will contribute to the evidence base for advice on lifestyle and metabolic modifications for cancer prevention. The clinical implications are two-fold. First, the findings will provide insight as to whether BA profiles are predictive of the efficacy of VSG with potential implications in personalized medicine, and second, identified biomarker profiles may be used for more refined risk stratification for development of these cancers and subsequent closer patients' surveillance for early detection "