Interleukin-35 as a predictor of prostate cancer in patients undergoing initial prostate biopsy

Background: Interleukin (IL)-35 is a novel inhibitory cytokine and has recently been implicated in tumor immunity. However, the role of IL-35 in prostate cancer (PCa) has not been elucidated. Objective: To evaluate the role of plasma IL-35 in the diagnosis and prognosis of PCa in Chinese patients undergoing initial prostate biopsy. Materials and methods: Using ELISA, plasma IL-35 levels were measured in 180 patients, who underwent a prostate biopsy. The clinical correlation of IL-35 with clinicopathological parameters was also evaluated. Univariate and multivariate logistic regression and receiver operating characteristic (ROC) curve analysis were performed to establish the role of IL-35 as a clinical biomarker. Results: Seventy-five (41.6%) of patients were histopathologically confirmed to have PCa. Plasma IL-35 levels were significantly higher in PCa patients (134.48 +/- 78.48 pg/mL) compared to non-PCa patients (67.22 +/- 24.08 pg/mL). ROC analysis showed that IL-35 was an independent predictor of PCa. Furthermore, IL-35 was found to be a significantly independent predictor of PCa in a group of patients with prostate-specific antigen levels between 4 and 10 ng/mL; was also able to predict advanced PCa from localized PCa and bone metastasis positive PCa from negative PCa. Conclusion: Our data suggest for the first time that plasma IL-35 levels are correlated with PCa and is the independent predictor of PCa progression and metastasis. Thus, IL-35 could be utilized as a potential biomarker for diagnosis and prognosis of PCa, could also aid in decision making and predict the stage of the disease.