In our meta-analysis, we found that SMAD4 expression is correlated with tumor differentiation, lymph node metastasis and TNM stage but not with the age or sex of NSCLC patients and SMAD4 expression is lower in NSCLC and is correlated with good OS of NSCLC patients. The gene discussed is SMAD4; the disease is metastatic malignant neoplasm in the lymph nodes.