Cyclooxygenase-2 (COX-2), epidermal growth factor receptor (EGFR), and Her-2/neu expression in ovarian cancer

Objectives. Cyclooxygenase-2 (COX-2) seems to be involved in critical steps of cancer onset and progression. Abnormalities of epidermal growth factor receptor (EGFR)and Her-2/neu have been actively investigated in ovarian cancer and associated with unfavorable clinical outcome. The involvement of COX-2 in ErbB family pathways has been proposed. We investigated by immunohistochemistry the expression of COX-2, EGFR, and Her-2/neu in a series of advanced primary ovarian cancers. Methods. The study included 76 consecutive stage IIIC-IV ovarian cancer patients with measurable disease after first surgery. Immunohistochemistry was performed on paraffin-embedded sections with rabbit antiserum against COX-2, murine monoclonal antibody (MoAb) 300G9 against Her-2/neu, and monoclonal antibody 108 against EGFR. Results. No association among COX-2, EGFR, and HER-2/neu was found. COX-2 positivity was found in a statistically significant higher percentage of unresponsive cases (80.0%) than in patients responding to chemotherapy (35.7%) (P = 0.0008). The association between COX-2 positivity and poor chance of response to treatment was retained in multivariate analysis. In the subgroup of patients who underwent explorative laparotomy COX-2-positive cases showed a shorter overall survival (P = 0.049). Conclusions. COX-2 could represent a possible new marker of sensitivity to platin-based chemotherapy in ovarian cancer. The lack of association of COX-2 with EGFR or Her-2/neu suggests that the ability of COX-2 to predict tumor sensitivity to chemotherapy is not dependent on EGFR or Her-2/neu status and could be independently associated with prognosis. In this context, the availability of agents able to specifically interfere with COX-2, Her-2/neu, or EGFR tyrosine kinase is of potential interest.