The usefulness of UGT1A1 polymorphism testing before starting irinotecan-based chemotherapy.

11055 Background: A few studies have revealed an association between UGT1A1 genotype and irinotecan-induced neutropenia. However, the usefulness of UGT1A1 polymorphism testing before starting irinotecan-based chemotherapy is controversial, even now. We assessed the clinical usefulness of UGT1A1 polymorphism testing before chemotherapy. Methods: 136 lung cancer patients were treated with nedaplatin and irinotecan combination chemotherapy as initial chemotherapy. Except for the patients with low enzyme activity of UGT1A1, 70 patients were treated after UGT1A1 polymorphism testing. (test group) 66 patients were treated without UGT1A1 polymorphism testing. (non-test group) We retrospectively analyzed adverse events and compared the test group with non-test group. Results: We could not confirm any reduction in hematologic or non-hematologic toxicity statistically in the test group. In 9 patients with non-hematologic toxicity of grade 4 and 5, 6 patients had febrile neutropenia (FN). All patients with FN were older than 70 years old. Adverse events in elderly patients were significantly more frequent than in the non-elderly. Conclusions: In patients treated with nedaplatin and irinotecan combination chemotherapy, UGT1A1 polymorphism testing before starting chemotherapy did not reduce adverse events. With UGT1A1 polymorphism testing only, it was difficult to predict the onset of severe adverse events. Therefore, it is more important to manage adverse events carefully, especially in elderly patients.