RASSF1 and metastatic malignant neoplasm in the lymph nodes: Among different pathological types and TNM stages, the highest positive rate of RASSF1A gene methylation was found in patients with adenocarcinoma and TNM stage IV LC (P < 0.05); the comparison of the positive rate of RASSF1A gene methylation among patients with different ages, genders, with or without smoking history, and with different histologic differentiation, maximum tumor diameter, and lymph node metastasis showed no statistically significant difference (P > 0.05).