PTGS2 and metastatic malignant neoplasm in the lymph nodes: The combined OR for COX-2 expression on high possibility of lymph node metastasis and advanced TNM stage were 1.28 (95% CI 1.03–1.60; p = 0.027) and 1.33 (95% CI 1.06–1.66; p = 0.015), suggesting that COX-2 expression was associated with tumor progression and metastasis.