The role of the gut microbiota in chemotherapy response, efficacy and toxicity: a systematic review

There is growing evidence for the relationship between the gut microbiota and the effect of chemotherapy. Therefore, this systematic review provides an overview of the current evidence on the effects of the gut microbiota on chemotherapy response, efficacy and toxicity in patients with cancer. PubMed, Web of Science, and EMBASE were searched to collect studies on cancer patients treated with chemotherapy that evaluated tumor response, efficacy, or toxicity, and included microbiome analysis through fecal samples. A total of 22 studies were included. Bacteria associated with better response in lung tumors were, amongst others, a relatively higher abundance of Streptococcus mutans, Enterococcus casseliflavus, and Bacteroides, while bacteria linked to response in gastrointestinal tumors included, among others, higher relative abundances of Lactobacillaceae, Bacteroides fragilis, and Roseburia faecis. Distinctive bacterial taxa were associated with clinical therapy, although causality was not proven. Targeting the gut microbiota during chemotherapy is considered to be a promising approach to enhance the response and to prevent toxicity of chemotherapy.