Clinical implementation of pre-treatment DPYD genotyping in capecitabine-treated metastatic breast cancer patients

Purpose Metastatic breast cancer (mBC) patients with DPYD genetic variants linked to loss of dihydropyrimidine dehydrogenase (DPD) activity are at risk of severe capecitabine-associated toxicities. However, prospective DPYD genotyping has not yet been implemented in routine clinical practice. Following a previous internal review in which two patients underwent lengthy hospitalisations whilst receiving capecitabine, and were subsequently found to be DPD deficient, we initiated routine DPYD genotyping prior to starting capecitabine. This study evaluates the clinical application of routine DPYD screening at a large cancer centre in London.