Comparative effectiveness of erlotinib versus no treatment for advanced non-small cell lung cancer patients in the Veterans Administration.

Abstract

6105 Background: Erlotinib (E) is FDA-approved for second-line treatment of unselected advanced non-small cell lung cancer (aNSCLC) patients. Clinical trials have shown increased response rates with E in aNSCLC patients having East Asian ethnicity, female gender, never-smoking history, or adenocarcinoma histology. The objective of this study was to compare the real-world effectiveness of E versus no treatment (NT) for first- and second-line treatment of aNSCLC patients in the Veterans Administration (VA). Methods: All incident aNSCLC cases diagnosed in the VA during 2007 were identified through the VA Central Cancer Registry, a subset of which underwent medical record abstraction through the VA External Peer Review Program. Abstracted records were then merged with national VA Decision Support System pharmacy and Corporate Data Warehouse encounters data through 2010. Treatment lines were determined through adaptation of a published algorithm. The impact of E versus NT on overall survival for each treatment line was then evaluated using 1:N greedy propensity score matching (PSM) and 2-stage residual inclusion (2SRI) estimation. Results: Among 1965 aNSCLC patients assessed for first-line treatment, 78 (4%) received E and 782 (40%) received NT; among 1124 assessed for second-line treatment, 128 received E (7%) and 638 (33%) received NT. 1:3 PSM of E cases to NT controls showed no difference in overall survival by Kaplan-Meier estimation in the first- (median 2.6 vs. 2.9 mos., p-value=0.86) and second-line (3.4 vs. 3.2 mos., p=0.85) settings. Chemotherapy use by Veterans Integrated Service Network was selected as the instrumental variable for 2SRI. Expected mean survival of E versus NT was similarly not statistically prolonged in the first- (E:NT survival time ratio 2.55, p=0.35) and second-line (2.49, p=0.32) settings. Conclusions: For a population with few aNSCLC patients having 3 out of the 4 clinicopathologic characteristics associated with improved response, E did not appear to confer a survival advantage over NT. Linking mutation results to observational datasets may improve comparative effectiveness research of personalized medicine in oncology.