EGFR and metastatic malignant neoplasm in the lymph nodes: The univariate analysis shown in Table 4 revealed that age at onset (P = .008), sex (P = .016), smoking history (P = .010), gene mutation status (P = .001), lymph node metastasis (P = .003) all had an effect on the incidence of brain metastasis, but no significant difference was found among the different mutation sites of EGFR (Table 4).