Elevated urinary total sialic acid and increased oxidative stress in patients with bladder cancer

Background: Increased production and release of sialic acid have been reported in many malignant conditions including bladder cancer. 8-hydroxydeoxyguanosine (8-OHdG) and malondialdehyde (MDA) have been widely used as oxidative stress biomarkers. Objective: Determine urinary levels of total sialic acid (TSA), 8-OHdG, and MDA in patients with urinary bladder cancer, and evaluate their clinical relevance. Patients and methods: Forty-five patients with histologically proven bladder cancer and 41 healthy subjects were recruited for the study. Morning urine samples were collected from all participants for measurements of TSA, 8-OHdG and MDA using thiobarbituric assay, competitive ELISA and spectrophotometry methods, respectively. Histological examination was performed for all patients. Results: Bladder cancer patients excreted urinary TSA, 8-OHdG, and MDA significantly higher than healthy controls. Based on receiver operating characteristic curve analysis, urinary TSA had adequate diagnostic potential to distinguish patients from healthy populations, and its cutoff value was chosen at 95.26 μg/g creatinine. Sensitivity, specificity, and accuracy of urinary TSA determination were 75.6%, 75.6%, and 75.6%, respectively. Both in patient and healthy groups, urinary TSA was linearly correlated with urinary 8-OHdG. Patients with highseverity grade (n=27) excreted urinary TSA significantly greater than those with low-severity grade (n=18). Conclusion: Urinary TSA, 8-OHdG, and MDA increased in patients with bladder cancer. The elevated urinary TSA was associated with enhanced oxidative stress. In addition, urinary TSA increased with progressiveness of the tumor.