Loss of P16 Expression and Chromosome 9p21 LOH in Predicting Outcome of Patients Affected by Superficial Bladder Cancer

Objectives: To evaluate the prognostic role of p16 expression and loss of heterozygosity (LOH) on chromosome 9p21 in patients affected by low-grade (G1-G2) urothelial bladder cancer. Methods: Fifty-six consecutive patients with diagnosis of urothelial bladder cancer were enrolled in this prospective study. LOH analysis was performed on a blood/tumor pair sample of each patient, by using polymerase chain reaction analysis. The D9S171 (9p21) locus on chromosome 9 was investigated. All tumors were stained immunohistochemically for p16. Data from p16 and LOH analyses were compared with follow-up data to evaluate the prognostic role of these molecular markers. Results: Loss of p16 expression was found in 33 patients (58.9%) and was significantly associated with the reduced recurrence-free probability (P < 0.0001). No correlations were reported with stage (P = 0.162) or grade (P = 0.051). Forty-three patients (76.7%) showed LOH on chromosome 9p21 (D9S171). A significant association was observed between loss of p16 expression and LOH on chromosome 9p21 (P = 0.005). The Kaplan-Meier curves showed a significant correlation between recurrence-free status and p16 expression (P = 0.0001). By multivariate analysis, p16 expression (P = 0.002) and number of lesions (P = 0.002) were identified as independent tumor recurrence factors. Conclusions: Our study highlights the prognostic role of p16 in predicting the recurrence-free probability in patients affected by low-grade urothelial bladder and highlights the fact that this method could be used in everyday urologic clinical practice to better characterize the natural history of urothelial bladder carcinomas. © 2007 Elsevier Inc. All rights reserved.