Prognostic factors for brain metastases from non-small cell lung cancer with EGFR mutation: influence of stable extracranial disease and erlotinib therapy

The aim of this study was to explore prognostic factors for non-small cell lung cancer (NSCLC) patients with brain metastases (BM) on the basis of EGFR mutation status. Among 779 consecutive NSCLC patients who underwent EGFR mutation screening, all 197 patients with BM were divided according to the EGFR mutation status. The prognostic factors, including patient characteristics at the time of BM diagnosis, treatment history, and radiologic features, were analyzed. Of 197 patients with BM, 108 had wild-type EGFR and 89 had EGFR mutation. The patients with EGFR mutation presented longer overall survival after BM diagnosis (OS) than those with wild-type EGFR, regardless of whether BM was synchronous or metachronous. For the patients with EGFR mutation, favorable prognostic factors in multivariate analysis were age <65 (p = 0.037), good performance status (PS) (p < 0.0001), cranial radiotherapy (p = 0.020), previous chemotherapy ≤1 regimen (p = 0.009), stable extracranial disease at BM diagnosis (p = 0.022), and erlotinib therapy after BM diagnosis (p = 0.0015). On the other hand, favorable prognostic factors for the patients with wild-type EGFR were only good PS (p = 0.0037) and cranial radiotherapy (p = 0.0005). Among patients treated with erlotinib after BM diagnosis, the patients with exon 19 deletion showed longer OS than those with exon 21 point mutation (p = 0.019). The prognostic factors for NSCLC patients with BM were different according to the EGFR mutation status. Particularly in NSCLC patients with EGFR mutation and stable extracranial disease, regular cranial evaluation for detecting asymptomatic BM would lead to good prognosis. In addition, erlotinib therapy would be preferable in NSCLC patients with BM and EGFR mutation, especially those with exon 19 deletion.