However, after adjustment for smoking history, histologic type, and lymph node metastasis, the promoter methylaton of each gene was more frequent in patients with pleural indentation compared with without pleural indentation (Table 5), particularly in CDH1(OR = 5.27, 95% CI = 1.27-21.9), DAPK1 (OR = 6.98, 95% CI = 1.06-45.8), and IRX2 (OR = 3.89, 95% CI = 1.01-15.0) genes, suggesting that promoter methylation of these genes may be a potential risk of pleural indentation in NSCLC. Here, IRX2 is linked to metastatic malignant neoplasm in the lymph nodes.