Of interest, RASSF1A methylation was negatively associated with smoking history, lymph node metastasis, and invasion or adhesion, respectively, although these associations did not reach statistical difference (Figure 3), suggesting that RASSF1A methylation may be an early event in lung tumorigenesis, which further confirmed a previous study. Here, RASSF1 is linked to metastatic malignant neoplasm in the lymph nodes.