The purpose of this review is to provide a practical and clinically relevant overview of the role of the microbiome in the development and treatment of digestive tract cancers. We describe the established associations between microbes and malignancy, such as Helicobacter pylori and Fusobacterium nucleatum, in gastric and colorectal cancer, respectively. We also review emerging evidence identifying additional microorganisms that may play a role in digestive tract cancer initiation and progression. We discuss the impact of microbial composition on the efficacy and toxicity of cancer-directed therapies, including radiation therapy and systemic chemotherapy. Beyond outlining gut microbial risk factors, we also highlight interventions on the oral and gut microbiome to prevent or alleviate symptoms associated with dysbiosis, along with proposed strategies to improve therapeutic outcomes in the future. Finally, we examine opportunities to support gut microbial health, including suggestions to reduce exposure to environmental toxins that may increase cancer risk.
Hotca et al. (2026) studied this question.