Prognostic impact of first treatment choice in EGFR mutant non-small cell lung cancer (mNSCLC) patients (pts) per mutation type; retrospective analysis.

e19120 Background: mNSCLC pts benefit from EGFR tyrosine kinase inhibitors (TKIs) but also from chemotherapy; the optimal sequencing of these treatments in not known. Methods: mNSCLC pts that received systemic treatment for stage 4 disease were eligible. De-identified data was retrieved from medical records of 6 cancer departments. Overall survival (OS) from diagnosis of metastatic disease was the primary outcome. Multivariate analyses included first line of treatment for metastatic disease (chemotherapy vs. TKI), EGFR mutation type, age, sex, stage at diagnosis, histologic subtype, smoking and performance status (PS). Based on our pilot study, to demonstrate OS HR ≥ 2.0 between pts treated with chemotherapy vs. TKI as first treatment, with significance level of 5% and power of 90%, we needed at least 88 events. Results: 287 pts were eligible, median age 66 years, 38% male, 76% stage 4 at diagnosis, 89% adenocarcinoma, 37% ever smokers, 79% PS 0-1. TKI was first treatment in 83%. Only stage at diagnosis (...