Gut microbiota in patients with metastatic or unresectable colorectal cancer receiving capecitabine

Previous pre-clinical research has indicated that the intestinal microbiota can potentiate anti-tumor efficacy of capecitabine/5-FU and that 5-FU-based treatment might impact intestinal microbiota composition and diversity. Using a longitudinal design, this study explored the associations between the intestinal microbiota and treatment response in patients with metastatic colorectal cancer (mCRC) during capecitabine treatment. Thirty-three Patients with mCRC treated with capecitabine were prospectively enrolled in a multicenter cohort study in the Netherlands. Patients collected a fecal sample and completed a questionnaire before, during, and after three cycles of capecitabine. Several clinical characteristics, including tumor response, toxicity and antibiotic use were recorded. Intestinal microbiota was analyzed by amplicon sequencing of the 16S rRNA V4 gene-region.