Discordance of Epidermal Growth Factor Receptor Mutation between Brain Metastasis and Primary Non-Small Cell Lung Cancer.

EGFR mutations were significantly discordant between primary tumors and corresponding metastases in a significant portion of NSCLC. In treatment of BM of EGFR mutant metastatic NSCLC, due to possibility of discordance, pathologic confirming through brain biopsy is recommended.