Five-Year Survival in EGFR-Mutant Metastatic Lung Adenocarcinoma Treated with EGFR-TKIs

Activating mutations in the epidermal growth factor receptor gene (EGFR) predict for prolonged progression-free survival in patients with advanced non-small cell lung cancer (NSCLC) treated with EGFR tyrosine kinase inhibitors (EGFR-TKIs) versus chemotherapy. Long-term survival outcomes, however, remain undefined. The objective of this study was to determine the 5-year survival in these patients and identify clinical factors associated with overall survival (OS).

Patients with EGFR-mutant metastatic lung adenocarcinoma who had been treated with erlotinib or gefitinib at Dana-Farber Cancer Institute between 2002 and 2009 were included. OS was analyzed.

Among 137 patients, median progression-free survival and OS were 12.1 months (95% CI: 10.2-13.5) and 30.9 months (95% CI: 28.2-35.7), respectively. Twenty patients (14.6%) were 5-year survivors. In multivariate analysis, exon 19 deletions (hazard ratio [HR] = 0.63, 95% CI: 0.44-0.91, p = 0.01), absence of extrathoracic (HR = 0.62, 95% CI: 0.41-0.93, p = 0.02) or brain metastasis (HR = 0.48, 95% CI: 0.30-0.77, p = 0.002), and not a current smoker (HR = 0.23, 95% CI: 0.09-0.59, p = 0.002) were associated with prolonged OS. Age; sex; stage at diagnosis; liver, bone, or adrenal metastasis; specific TKI; and line of TKI therapy were not associated with OS.

Our data suggest that the rate of 5-year survival among patients with EGFR-mutant metastatic lung adenocarcinoma treated with erlotinib or gefitinib is 14.6%. Exon 19 deletions and absence of extrathoracic or brain metastasis are associated with prolonged survival. On the basis of our findings, clinicians can gain an enhanced estimation of long-term outcomes in this population.