Impact of serum interleukin-18 level as a prognostic indicator in patients with epithelial ovarian carcinoma

Background. Interleukin-18 (IL-18), a cytokine produced by macrophages, is capable of inducing T-lymphocyte synthesis of interferon-γ (IFN-γ). In this study, for the first time, the serum concentration of IL-18 and its significance as a prognostic indicator was evaluated in patients with epithelial ovarian cancer. Methods. The serum IL-18 level was measured by an enzyme-linked immunosorbent assay (ELISA) in 69 patients with epithelial ovarian cancer and 8 healthy controls. Relationships between the IL-18 level and clinicopathological features were examined by univariate and multivariate analyses. Results. The median serum IL-18 level in the ovarian cancer patients was 229.6 pg/ml, and the level was significantly elevated compared with that in the normal controls (151.3 pg/ml; P < 0.01). No significant correlations were detected between the IL-18 level and stage or histology (P = 0.08 and P = 0.12, respectively). On univariate analysis, overall survival was shown to be affected by IL-18 serum levels. However, multivariate analysis failed to demonstrate an independent prognostic significance for IL-18 serum levels, while confirming the role of previously established prognostic variables, such as performance status, stage, and residual tumor. Conclusion. This study showed that IL-18 serum levels were elevated in ovarian cancer patients and were correlated with overall survival, although they were shown not to be an independent prognostic factor.