A study in The Journal of Molecular Diagnostics evaluated whether the size and integrity of urine cell-free DNA (cfDNA) can support bladder cancer detection and staging. Current tools such as cystoscopy are invasive, and urine cytology lacks sensitivity for many tumors, prompting interest in alternative laboratory markers.
Researchers analyzed urine from 156 patients with bladder cancer and 79 matched controls. Using real-time PCR, they measured large (>250 base pairs) and small (<125 base pairs) cfDNA fragments from several genes, including ACTB, AR, and MYC. Concentrations of many fragments increased with disease severity, with the most consistent changes seen in ACTB, AR, and the small MYC fragment.
One of the most informative measures was the ACTB integrity ratio (large/small fragments). This ratio was lowest in controls and increased steadily through non–muscle-invasive cancer (NMIBC) and muscle-invasive cancer (MIBC), suggesting that necrosis-related cfDNA release rises with tumor progression.
The small MYC fragment showed the strongest individual diagnostic performance. Its receiver operating characteristic (ROC) curve reached an AUC of 0.7221 for identifying all bladder cancer cases and 0.8098 for distinguishing MIBC from controls. Specificity was high at 95 percent, although sensitivity was moderate at 50 percent.
A small subset of patients with serial urine samples showed that increases in ACTB integrity, small AR fragments, and small MYC fragments may signal tumor relapse, suggesting possible use in follow-up monitoring.
These results indicate that urine cfDNA fragmentation patterns – especially ACTB integrity and the small MYC fragment – may offer a noninvasive complement to existing tests. Such assays may help identify higher-stage disease and may provide additional information when cytology is inconclusive.
Limitations included incomplete amplification of some fragments (STOX1 and large MYC), moderate sensitivity of the MYC marker, and limited availability of cytology data for comparison. The authors conclude that larger validation studies are needed.
Newsletters
Receive the latest pathologist news, personalities, education, and career development – weekly to your inbox.
