Spearman coefficient of correlation showed that the positive CDK5 expression in SCLC was correlated with gender (r = 0.418, P = 0.034), TNM stages (r = 0.415, P = 0.049), and lymph node metastasis (r = 0.469, P = 0.024, Table 5). This evidence concerns the gene CDK5 and metastatic malignant neoplasm in the lymph nodes.