Implementation of Pre-emptive Geno- and Phenotyping in 5-Fluorouracil- or Capecitabine-treated Patients

The aim of this study is to investigate if the systematic implementation of pre-emptive geno- and phenotyping, and therefore a dose reduction based on the French guidelines and the literature during the first month of treatment, reduces grade 3 or greater toxicity in patients treated with 5-FU (5-fluorouracil) or capecitabine.
Therefore, a monocentric, partial prospective and partial retrospective trail was designed.