These data suggest that DPD activity, by modulating plasma concentration, may be a predictive factor of fluoropyrimidine response and also a prognostic factor. To our knowledge, there are no studies that have demonstrated a direct link between DPD activity, tumor response, and survival impact. Recently, Chamorey and al. [10] showed that the high level of DPD enzyme activity (> 0.30 nmol / min / mg protein) was significantly correlated with lower overall survival and progression-free survival. This was a retrospective analysis of 130 patients treated with fluoropyrimidines regardless of the tumor primitive (digestive, breast, ENT).