Studies have shown [79] that the expression of E-cad in tumor tissues of patients with LCBM is significantly lower than that in tumor tissues and paracancerous tissues of patients with lung cancer without brain metastasis, and this mechanism may be the hypermethylation of the promoter region of the E-cad gene, which suggests that E-cad can be used as a predictive indicator of LCBM. This evidence concerns the gene CDH1 and lung cancer.