Cyclooxygenase-2 Overexpression Predicts Poor Survival in Patients with High-grade Extremity Osteosarcoma: A Pilot Study

Several lines of evidence suggest cyclooxygenase-2 (COX-2) overexpression may be a causal factor for tumor growth and metastasis. However, there is no evidence COX-2 expression in a primary tumor correlates with clinical outcome of osteosarcoma. We examined expression levels of COX-2 immunohistochemically in 51 patients with extremity osteosarcoma who completed standard therapy and obtained complete initial regression of the tumor. Correlation of the positivity of staining with prognosis was analyzed. COX-2 was expressed in most of the cases. We found no correlation between COX-2 staining intensity and variables such as gender, age, anatomic site, necrosis after chemotherapy, and surgical stage. Strong COX-2 expression was associated with low metastasis-free survival. Age older than 20 years and strong COX-2 expression independently predicted increased risk of metastasis. Among seven patients with resectable lung metastasis, all three with greater COX-2 expression in the metastatic lesion than that in a primary site died of the disease. Our preliminary data suggest COX-2 overexpression in the primary tumor correlates with the occurrence of distant metastasis in patients with osteosarcoma and also may affect postmetastatic survival.