Prognostic significance of iNOS in epithelial ovarian cancer

ObjectiveTo study the association of inducible nitric oxide synthase (iNOS) expression with clinicopathological factors and prognosis in epithelial ovarian cancer.MethodsThe study included 301 patients with primary epithelial ovarian cancer. iNOS expression was evaluated by immunohistochemistry using a mouse monoclonal antibody.ResultsiNOS positivity was observed as granular deposits in the cancer cell cytoplasm. The mean percentage of iNOS-positive cells was 50% in primary tumors (n = 301), and 62% in metastatic lesions (n = 43). iNOS expression correlated significantly with histological subtype of the tumor, as high (> 70%) iNOS expression was observed in mucinous tumors (p = 0.009). Poorly differentiated tumors showed a tendency to low (≤ 70%) iNOS expression but without statistical significance. Low iNOS expression associated also significantly with large primary residual tumor (p = 0.007) and tumor recurrence (p = 0.04). The 10-year prognosis of the patients with high iNOS expression was better in disease-related survival (DRS) (p = 0.009). However, in multivariate analysis only FIGO stage, primary residual tumor, and grade of the tumor were independent prognostic factors for DRS, but not the iNOS expression.ConclusionsA major proportion of human epithelial ovarian cancers expressed iNOS. The positive expression was an indicator of better disease-related survival. However, iNOS positivity could not overcome the importance of clinicopathological factors in prediction of prognosis.