Intestinal Microbiota Composition is Predictive of Radiotherapy-induced Acute Gastrointestinal Toxicity in Prostate Cancer Patients

The search for factors beyond the radiotherapy dose that could identify patients more at risk of developing radio-induced toxicity is essential to establish personalised treatment protocols for improving the quality-of-life of survivors. To investigate the role of the intestinal microbiota in the development of radiotherapy-induced gastrointestinal toxicity, the MicroLearner observational cohort study characterised the intestinal microbiota of 136 (discovery) and 79 (validation) consecutive prostate cancer patients at baseline radiotherapy. Gastrointestinal toxicity was assessed weekly during RT using CTCAE. An average grade >1.3 over time points was used to identify patients suffering from persistent acute toxicity (endpoint). The intestinal microbiota of patients was quantified from the baseline faecal samples using 16S rRNA gene sequencing technology. Intestinal microbiota of prostate cancer patients was profiled before radiotherapy from faecal samples using 16S rRNA gene sequencing technology and processed using the Ion Reporter metagenomic pipeline