Role of Cyclooxygenese-2 (COX-2) Expression in Breast Cancer Differentiation and Its Relationship with Hormone Receptors Status

Background and Objectives: Cyclooxygenese-2 (COX-2) expression in breast cancer and its correlation with tumor prognosis is unclear. We investigated the incidence of COX-2 expression in patients and assessed interactions between COX-2 and clinical features of cancer and expression of HER2/neu, estrogen receptor (ER), and progesterone receptor (PR). Methods: COX-2 expression was investigated by immunohistochemistry in 29 patients’ specimens diagnosed as primary breast cancer between 2006 and 2008 at the Fatemieh Hospital, Semnan, Iran. Relationship between COX-2 expression and age, histological grade, histological type, nodal status, and hormone receptor status were evaluated. Results: We used IHC method although it was not a quantitative study. Its expression depends on quality of antibody, staining and selection of analyzed region. COX-2, HER-2, ER, and PR were detected in 89.7%, 51.7%, 82.8%, and 79.3% of samples, respectively. Elevated COX-2 expression was not associated with size and grade of tumor, while mean numbers of involved lymph nodes was significantly higher in those with elevated expression of COX-2 (P = 0.001). There were no significant correlations between COX-2 expression and HER-2, ER, and PR receptors. Conclusion: Only tumor tissue was analyzed and did not compare to normal tissue. Elevated COX-2 expression can be found in most patients with breast cancer and has a crucial role in tumor differentiation regarding degree of lymph node involvement. It seems that correlation between COX-2 and other oncogens and hormonal receptors might be influenced by geographical and racial factors, so, assessment of these relationships in each patient's population may be necessary.