Exon 19 deletion of epidermal growth factor receptor is associated with prolonged survival in brain metastases from non-small-cell lung cancer

Brain metastasis (BM) is a poor prognostic factor for non-small-cell lung cancer (NSCLC). Recent studies have shown that oral epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) were effective for BM from NSCLC with EGFR mutation. However, the relationship between EGFR mutations and prognosis of NSCLC BM patients remains to be determined. In this study, we investigated the impact of EGFR mutation status on the survival of BM patients from NSCLC. One hundred six patients with BM from NSCLC were retrospectively reviewed. Thirty-three subjects (24.3 %) were confirmed to have an exon 19 deletion, while another 33 had an exon 21 point mutation (L858R) (24.3 %). Log-rank test and Cox proportional hazards model were used to analyze the impact of variables on survival. The median survival of NSCLC with BM was 8 months. Log-rank test analysis showed that Eastern Cooperative Oncology Group Performance Status (ECOG-PS) at BM (p < 0.0001), control of primary tumor (p = 0.005), pathology (p = 0.01), EGFR mutations (p = 0.045), and 19 exon deletion (p = 0.007) were associated with a longer survival. In a Cox proportional hazards model, EGFR exon 19 deletion (p = 0.034), control of primary tumor (p = 0.024), and ECOG PS at BM (p = 0.006) were found to be independent prognostic factors. Moreover, there were prognostic differences between groups according to Radiation Therapy Oncology Group (RTOG) recursive partitioning analysis (RPA) classification system (p < 0.0001). Exon 19 deletion is an independent prognostic factor in BM from NSCLC. It should be integrated into the prognostic scoring classification system for NSCLC.