PTGS2 and cancer: COX‐2 expression was not correlated with age, gender, tumor location, cancer histology, or necrosis (P > 0.1), but was significantly associated with tumor grade (high grade vs. low grade: OR = 4.81, P < 0.001), clinical stage (stage 3–4 vs. stage 1–2: OR = 4.89, P < 0.001), and metastasis (yes vs. no: OR = 3.53, P < 0.001).