EGFR and neoplasm: No significant differences were observed in terms of age, gender, stage, initial clinical tumor and nodal classification, extracranial metastases, histological grading, EGFR mutation, primary lung surgery, number of lines of chemotherapy, name of EGFR-TKI, number of lines of TKI, mean duration of TKI use, smoking history, ECOG performance status at the time of BM, and dsGPA (all p > 0.05; Table 1).