Frequency of brain metastases in non-small-cell lung cancer, and their association with epidermal growth factor receptor mutations

Background The brain is a frequent site of metastases from non-small-cell lung cancer (NSCLC). We analyzed the frequency of brain metastases (BMs) from NSCLC in the era of magnetic resonance images, and evaluated the correlation between epidermal growth factor receptor (EGFR) mutations and BMs among East Asian patients. Methods Frequency, number, and size of BMs, and survival of 1,127 NSCLC patients were retrospectively reviewed. Mutation status of EGFR was evaluated in all cases, and its association with BMs was statistically evaluated. Results EGFR mutations were found for 331 cases (29.4 %). BM was the cause of primary symptoms for 52 patients (4.6 %), and found before initiation of treatment for 102 other patients (9.1 %); In addition to these 154 patients, 107 patients (9.5 %) developed BMs, giving a total of 261 patients (23.2 %) who developed BMs from 1,127 with NSCLC. BM frequency was higher among EGFR-mutated cases (31.4 %) than EGFR-wild cases (19.7 %; odds ratio: 1.86; 95 % confidence interval (CI) 1.39-2.49; P < 0.001). BMs from EGFR-mutated NSCLC were small, but often became disseminated. EGFR mutations accounted for 39.9 % of BMs, but patient survival after BMs was significantly longer for EGFR-mutated cases than for EGFR-wild cases (hazard ratio: 2.23; 95 % CI 1.62-3.10; P < 0.001). Conclusion Patients with EGFR-mutated NSCLC were more likely to develop BMs, but apparently also survived longer after BMs.