Cyclooxygenase-2 Expression in Brain Metastases

Abstract

Background: Elevated Cyclooxygenase-2 (COX-2) expression is thought to increase metastatic potential of many tumors. Furthermore, elevated COX-2 expression correlates with radiation resistance in many tumor types. We evaluated whether: (i) the degree of COX-2 expression correlated with either metastatic tumor type or with the presence of necrosis and whether (ii) radiation-resistant tumors (renal cell and melanoma) had higher expression of COX-2 than did relatively radiation-sensitive tumors (breast and lung). Materials and Methods: Specimens from sixteen patients who underwent resection of brain metastases were analyzed for COX-2 expression using a COX-2 antibody-based immunoassay. Specimens consisted of brain metastases from lung tumors, breast adenocarcinomas, melanomas and renal cell carcinomas. All specimens were analyzed for the presence or absence of necrosis. Results: Ten of sixteen brain metastasis specimens had ten percent or less Cox-2 immunostaining. Statistical analyses showed no correlation between Cox-2 immunostaining and metastatic tumor type or between Cox-2 immunostaining and necrosis in this study. Furthermore, renal cell carcinoma and melanoma showed variable Cox-2 immunostaining. Conclusion: Cox-2 is not consistently expressed in metastases to the brain. The degree of Cox-2 expression does not correlate with metastatic tumor type or with the presence of necrosis. Radioresistant tumors did not have statistically different expression of Cox-2 than radiosensitive specimens studied in this analysis.