People undergoing cancer therapy commonly experience a broad range of adverse side effects, with substantial inter-individual variability. This heterogeneity complicates clinical management and often leads to reactive rather than proactive care. Although numerous studies have sought to identify predictors of treatment toxicity—including host-, disease-, and treatment-related factors—few have translated into routine clinical practice due to limitations in sensitivity, specificity, or feasibility.
More recently, the gut microbiota has emerged as a critical and underexplored determinant of treatment response and toxicity. As a highly individualised and dynamic ecosystem—akin to a fingerprint—the gut microbiota plays a central role in modulating host physiology. In cancer therapy, it influences drug metabolism and pharmacokinetics, and affects immune, endocrine, and neural pathways. Increasing evidence now shows that distinct microbial features can predict susceptibility to a wide array of treatment-related side effects.
Importantly, the gut microbiota is itself a target of collateral damage during cancer therapy. Profound shifts in microbial composition and function have been linked to multiple toxicities, including mucositis, diarrhoea, cognitive impairment, fatigue, psychological distress, and peripheral neuropathy. These insights are fuelling interest in microbiota-targeted interventions as a new frontier in supportive cancer care.
This presentation will explore the emerging evidence base for using the gut microbiota to stratify patient risk, personalise supportive care strategies, and develop novel microbiome-based interventions aimed at reducing the burden of cancer treatment.