The present letter focuses on the pharmacogenetic (PGx) testing of variants of the dihydropyrimidine dehydrogenase (DPYD) gene available at Instituto Nacional de Câncer (INCA), Rio de Janeiro, for cancer patients who are candidates for treatment with the fluoropyrimidines 5-fluorouracil (5-FU) and/or capecitabine.1 The rationale for DPYD genotyping is as follows:...