Comparison of the Incidence and Pattern of Interstitial Lung Disease During Erlotinib and Gefitinib Treatment in Japanese Patients with Non-small Cell Lung Cancer The Okayama Lung Cancer Study Group Experience

Background: Data comparing the incidence and pattern of interstitial lung disease (ILD) in non-small cell lung cancer patients receiving treatment with gefitinib versus erlotinib, both of which are epidermal growth factor receptor tyrosine kinase inhibitors, are scarce. We investigated the incidence of ILD in Japanese patients treated with gefitinib or erlotinib. Methods: We reviewed the clinical records of 209 patients treated with erlotinib in 2008 (cohort A) and 330 treated with gefitinib between 2000 and 2003 (cohort B). Toxicity within the first month of treatment was investigated. Results: The patients in cohort A had fewer known risk factors for ILD (e.g., poor performance status and prior pulmonary fibrosis). ILD was detected in two patients (1.0%) from cohort A and eight patients (2.4%) from cohort B during the first month of treatment. The events were graded as follows: one patient each in grades I and 2 (cohort A), and one, one, and six patients in grades 3, 4, and 5, respectively (cohort B). Multivariate analysis revealed that poor performance status and prior pulmonary fibrosis were significantly correlated with the occurrence of ILD, but the type of epidermal growth factor receptor tyrosine kinase inhibitor administered was not. Conclusion: There was a somewhat lower incidence of ILD with erlotinib therapy than with gefitinib therapy, despite no statistically significant difference. Patient selection based on awareness by Japanese physicians of the risk factors for ILD, rather than the type of agent, may explain the difference in ILD incidence between the two treatments.