In the LUX-Lung 6 trial, the median PFS of patients with brain metastases treated with afatinib was lower than that of patients without brain metastases [47], which was in accordance with our results, suggesting that brain metastases is an influence factor of patients with advanced EGFR-mutant NSCLC based on afatinib dose. The gene discussed is EGFR; the disease is non-small cell lung carcinoma.