Overall response to first-line tyrosine Kinase inhibitor and second-line chemotherapy is predictive of survival outcome in epidermal growth factor receptor-mutated adenocarcinoma

Background: First-line epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are effective for the treatment of lung adenocarcinoma with an EGFR-sensitizing mutation, but resistance is inevitable. Chemotherapy is widely used in the second-line setting. The outcome following this treatment scheme has not been thoroughly evaluated. Methods: From 2007 to 2011, consecutive patients with mutated EGFR receiving first-line TKI and second-line chemotherapy were retrospectively reviewed. The overall response was categorized into double responder, single responder and double nonresponder. Results: Following this treatment scheme, baseline Eastern Cooperative Oncology Group (ECOG) performance status 0-1 (HR 0.60; 95% CI 0.37-0.98; p = 0.041) and double responder (HR 0.24; 95% CI 0.07-0.78; p = 0.018) were independent predictors of overall survival. Absence of pleural metastasis independently predicted the response to first-line TKI (OR 2.60; 95% CI 1.13-5.99; p = 0.025). In TKI responders, ECOG performance status 0-1 before chemotherapy (OR 4.95; 95% CI 1.15-21.28; p = 0.006), an exon 19 deletion (OR 4.74; 95% CI 1.30-17.21; p = 0.018) and progression-free survival (PFS) on first-line TKI (OR 1.02; 95% CI 1.01-1.09; p = 0.049) independently predicted the response to second-line chemotherapy. A moderate linear relationship (Pearson's r = 0.441; p = 0.001) existed between the PFS of this treatment scheme in TKI responders. Conclusion: The status of double responder to first-line TKI and second-line chemotherapy was predictive of improved survival in EGFR-mutated adenocarcinoma.