Intestinal microbiota in colorectalcancer

Interventions: An explorative prospective multicenter cohort study in the Maastricht University Medical Centre+, Catharina Hospital and Zuyderland Medical Centre will be performed in 66 patients. Before, during, and after three cycles of systemic treatment with capecitabine or TAS-102, fecal samples and questionnaires (concerning compliance and chemotoxicity) will be collected. The response will be measured by CT/MRI using RECIST-criteria. Fecal microbiota composition will be analyzed with 16S rRNA next-generation sequencing. The absolute bacterial abundance will be assessed with quantitative polymerase chain reaction. Multivariate analysis will be used for statistical analysis. Primary outcome(s): Microbiota composition before, during and after 3 cycles systemic treatment with capecitabine or TAS-102 related to respons & chemotoxicity Study Design: N/A , unknown, Other