Brain metastasis features and association with tumor epidermal growth factor receptor mutation in patients with adenocarcinoma of the lung

Aim: Epidermal growth factor receptor (EGFR) mutations are frequent in pulmonary adenocarcinoma patients. The association between tumor EGFR mutation and characteristics of brain metastasis (BM) is still unclear. Methods: We retrospectively reviewed pulmonary adenocarcinoma patients with and without BMs, and characteristics of BM to analyze the association between tumor EGFR mutation and characteristics of BM. Results: Of 374 cases, 239 had EGFR mutations; 69 had BM at initial diagnosis, and 82 with BMs after treatment. All eligible patients received EGFR-tyrosine kinase inhibitors treatment. Older patients (≥70 years old) were less likely to have BMs than younger patients (25.8% vs 48%, P < 0.001). Patients with higher N stage had higher proportion of BMs (P = 0.006). Patients with exon 19 deletion were more likely to have BMs than those without EGFR mutation (48.1% vs 34.1%, P = 0.021). Patients with exon 19 deletion didn't have significantly higher chance of BMs at initial diagnosis but had higher chance to develop BM after treatment than those without EGFR mutation (35.6% vs 21.2%, P = 0.019). Patients with exon 19 deletion survived longer than those without EGFR mutation (1-year survival rate 95.8% vs 78.7%, P = 0.003). Thus, longer survival may lead to higher proportion of BM occurrence in patients with exon 19 deletion than those without EGFR mutation. Conclusions: In pulmonary adenocarcinoma, there is no significant difference in frequency of BMs at initial diagnosis between patients with EGFR mutation and wild type. However, after treatment, patients with EGFR mutations are significantly more likely to develop BM.