Background: 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.
Method: This cross-sectional study was conducted on 88 participants with colorectal cancer (CRC). After DNA extraction, polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used to determine the DPD gene (DPYD) polymorphisms including IVS 14 + 1 G > A, 2846 A > T and 2194 G > A. Chemotherapy-induced side effects were evaluated according to the Common Terminology Criteria for Adverse Events (CTCAE Version 5.0).
Result: Data were collected from 227 chemotherapy cycles of 88 patients with CRC. In a comparison of FOLFOX and FOLFIRI regimens, there was no significant difference in the occurrence of chemotherapy-induced diarrhea, nausea, vomiting and oral mucositis. However, the peripheral neuropathy was more frequent in patients who were treated with FOLFOX (P < 0.001) and hair loss was more common in patients who received FOLFIRI regimen (P = 0.048). Incidence of the DPD IVS14 + 1 G > A polymorphism was observed in four patients (5.5%). There was no association between IVS14 + 1 G > A polymorphism and the occurrence of adverse reactions.
Conclusion: FOLFOX and FOLFIRI were the most common regimens in CRC patients and their toxicity profile was different in some adverse reactions. Prevalence of IVS14 + 1G > A variant was relatively higher than other similar studies.
Trial registration: Approval code; IR.MAZUMS.REC.95.2480.
Keywords: 5-fluorouracil; Colorectal cancer; Dihydropyrimidine dehydrogenase; Polymorphism; Side effects.