ALK and metastatic malignant neoplasm in the lymph nodes: It was found that only positive EGFR mutations (P = .012), positive ALK gene fusion (P = .015), and positive RET gene fusion (P = .003) were independent risk factors for brain metastasis, and that a young age, lymph node metastasis, and histological type (adenocarcinoma) were also independent risk factors for brain metastasis.