Association Between Positive iNOS mRNA Expression and Recurrence-free Survival Among Patients with Non-muscle-invasive Bladder Cancer

Objective: Nitric oxide synthase is the key enzyme of the conversion of L-arginine to L-citrulline and nitric oxide. We conducted a study to investigate the association between positive inducible nitric oxide synthase (iNOS) mRNA expression and recurrence of bladder cancer.Patients and Methods: Seventy-one patients with primary non-muscle-invasive bladder cancer were enrolled in this study. Tumor tissues were harvested during transurethral resection of bladder tumors. All operations were performed at the same hospital. Recurrence-free patients were followed up for at least 1 year unless tumors recurred during that time. The median intervals of follow-up were 34 months in the recurrence-free group and 12 months in the recurrence group. iNOS mRNA was detected using the RT-PCR-based method.Results: Bladder cancer patients with positive iNOS mRNA expression had a higher recurrence risk (18.7% vs. 2.6%; p=0.04). After adjusting for other risk factors, a statistical significance remained (p=0.04; hazards ratio =13.27; 95% CI = 1.07-164.36). The patients also had reduced recurrence-free survival (p=0.019).Conclusion: The positive expression of iNOS mRNA may be a useful prognostic indicator of bladder cancer.