Urinary cell-free DNA as a potential tumor marker for bladder cancer

The objective was to assess the possibility of measuring urine creatinine (UCr)-adjusted urinary cell-free (ucf) DNA concentration as a noninvasive screening tool for bladder cancer. Using PicoGreen-based detection, the ucf-DNA/UCr concentration was quantified in urine supernatant specimens from 46 bladder cancer patients and 98 controls and compared to 400-bp real-time PCR-based detection, which detected the amplification of 400-bp beta-actin (named 400-bp ucf-DNA/UCr). The mean concentrations for both PicoGreen and 400-bp ucf-DNA (ng/mL)/UCr (mg/dL) were significantly higher in bladder cancer patients than in controls: 15.28 vs 6.68 (p<0.001, t-test) and 14.98 vs 1.07 (p<0.001), respectively. Among different stages and grades, no significant difference was found between these two methods. The areas under the ROC curves of PicoGreen and 400-bp ucf-DNA/UCr were 0.571 (95% confidence interval, 0.451-0.692) and 0.805 (95% confidence interval, 0.713-0.896), respectively. In 400-bp ucf-DNA/UCr, the best sensitivity and specificity were 86.1% and 72.0% at the cutoff value of 0.0645. These data indicated that 400-bp ucf-DNA/UCr is more reliable for bladder cancer detection than PicoGreen. In conclusion, our results suggest that ucf-DNA/UCr can be used as a potential tumor marker for bladder cancer, especially for detecting longer DNA fragments.