Expression of COX-2 and HER-2 in human breast cancer and their relationship

Objective: To study the expression of cyclooxygenase-2 (COX-2) and HER-2 in human breast cancer and their relationship. Methods: Archival breast carcinoma (n = 80), atypical hyperplasias (n = 27) and normal breast epithelia (n = 20) were analyzed for COX-2 and HER-2 expression by immunohistochemistry using specific monoclonal antibodies. Results: COX-2 was expressed in 57. 5% (46/80) of breast carcinomas at a moderate to high level, which was significantly different from the expression in benign breast epithelia. COX-2 expression was correlated with histological grade, lymph node metastasis, TNM stage and ER state (P<0.05 or P< 0.01). HER-2 was overexpressed in 37.5% (30/80) of breast carcinomas. HER-2 expression level was correlated with TNM stage, lymph node metastasis, histological grade, ER state and PR state (P<0.05 or P<0.01). The expression of COX-2 in HER-2 positive breast cancers was significantly higher than that in HER-2 negative breast cancers. Conclusion: Both COX-2 and HER-2 overexpression is significantly related to the biological behavior of human breast cancer. COX-2 is probably one of the most important mediators of HER-2 tumorigenic pathway.