DOI: 10.36347/sasjm

Pages: 172-176

There are individual differences in the amount of administered opioid required in cancer patients, but genetic factors are not only related to their clinical state. Genetic polymorphisms in catechol-O-methyltransferase (COMT), a metabolic enzyme of catecholamines, are suggested to be responsible for differences in pain sensitivity. We examined the correlation between COMT gene polymorphism and administered opioid dose and the dosage increase during the administration period in gastrointestinal cancer patients treated at our hospital. Twenty-four patients with gastrointestinal cancer who underwent surgical resection at our hospital and had surgical specimens were included. Total DNA was extracted from the paraffin-embedded specimen and the gene polymorphism of COMT was measured by genotyping assay. The administered opioid dose and the period from the start of opioid administration to the maximum dose for each case were examined, and the increment per day was compared between each single nucleotide polymorphism (SNP). Among 24 cases, one case was A/A type (4.2%), 11 were A/G (45.8%), and 12 were G/G (50.0%). No significant difference was observed in the maximum dose between A/G or G/G (p = 0.76). The administered dose increment per day was larger in the case of A/G type than for G/G (p = 0.04). In this study, it was shown that the A/G type cases require more opioid in a certain period of time than G/G type cases. For these cases, it was considered that prompt adjustment of the optimum opioid dose administered was necessary according to the patient's pain complaints