The Usefulness of Serum X-linked Inhibitor of Apoptosis Protein (XIAP) for Predicting Recurrence of Low-Grade Renal Cell Carcinoma

Abstract

The X-linked Inhibitor of Apoptosis Protein (XIAP) has been associated with cell survival because it blocks caspase-mediated apoptosis. The expression of XIAP and its prognostic significance in Renal Cell Cancer (RCC) have rarely been studied. Objective: To evaluate the usefulness of serum XIAP levels in RCC patients as a biomarker for predicting recurrence after surgery. Methods: Peripheral blood samples were obtained from 88 patients (67 males and 21 females; median age, 60.0 years) with RCC before surgery. All of the patients underwent radical or partial nephrectomy. Blood samples were also collected from 52 healthy controls. The serum XIAP levels were measured by ELISA. The cut-off value was calculated by ROC analysis. Recurrence-free survival was evaluated in all patients. Results: The mean serum XIAP levels in patients with RCC were higher than those of normal control individuals (239.8 pg/ml vs. 156.2 pg/ml, P<0.001). At a median follow-up of 48 months (3-105 months), tumors with low serum XIAP showed significantly longer recurrence-free survival than those with high serum XIAP in the Grade 1-2 group (n=75) (P<0.05). Conclusion: Serum XIAP level is associated with recurrence and prognosis of RCC patients, especially in patients with the lower nuclear grade of 1 and 2. These results suggest that it may be used as a novel biomarker for predicting prognosis.