5-Fluorouracil (5-FU) and capecitabine are fluoropyrimidine derivatives that mainly metabolized with dihydropyrimidine dehydrogenase enzyme (DPD). The genetic polymorphism in the genes encoding this enzyme may result in a decrease or loss of enzyme activity which may lead to the accumulation of medicines, their metabolites and potential toxicity. | Evaluation of adverse effects of chemotherapy regimens of 5- fluoropyrimidines derivatives and their association with DPYD polymorphisms in colorectal cancer patients