ctDNA is not a simple positive/negative binary test. Like PSA in prostate cancer, the quantitative level of ctDNA correlates with patient outcomes. Higher levels indicate a worse prognosis and a faster time to relapse, allowing for more nuanced risk stratification beyond a simple presence or absence of the biomarker.

Circulating tumor DNA is a powerful tool for detecting systemic minimal residual disease but is not sensitive enough for local, non-muscle invasive recurrences. This limitation means traditional surveillance like cystoscopy remains indispensable, as a negative ctDNA test can provide a false sense of security about local control.

Circulating tumor DNA (ctDNA) is a powerful biomarker for identifying high-risk bladder cancer patients. However, its imperfection presents a new clinical dilemma: with a ~12% relapse rate even in ctDNA-negative patients, clinicians must decide whether to withhold adjuvant therapy and accept that risk, or overtreat the 88% who are likely cured.

Contrary to assumption, persistent ctDNA after neoadjuvant therapy does not always mean incurable systemic disease. Surgery alone can clear the ctDNA in roughly half of these patients, suggesting the ctDNA source is often the resectable primary tumor, making cystectomy a potentially curative intervention.

Professor Powles highlights a critical limitation of ctDNA in bladder cancer management. While excellent for assessing systemic risk, ctDNA may remain negative during a local, non-muscle invasive relapse (e.g., T1 cancer). This necessitates continued local surveillance like cystoscopy, even in ctDNA-negative patients pursuing bladder-sparing approaches.

The future of bladder cancer surveillance may involve using two types of liquid biopsies in tandem. A patient who is utDNA-positive but ctDNA-negative likely has a local, primary bladder issue. Conversely, a utDNA-negative but ctDNA-positive result suggests the cancer has already spread systemically, providing crucial information for treatment planning.

Beyond a simple positive/negative result, the quantitative level of ctDNA is highly prognostic in bladder cancer. Similar to PSA in prostate cancer, higher ctDNA levels correlate with a significantly worse prognosis, offering a more nuanced risk assessment tool than a binary test.

Experts suggest urinary tumor DNA (utDNA) may better reflect local disease in the bladder, while circulating tumor DNA (ctDNA) indicates systemic disease. Using both tests in parallel could provide a more complete picture, with dual-negative results potentially becoming a key criterion for safely pursuing bladder-sparing approaches.

A positive ctDNA (blood) but negative utDNA (urine) test suggests systemic, metastatic disease. Conversely, a positive utDNA with negative ctDNA points to a tumor confined to the bladder. This integrated biomarker approach can help determine whether systemic therapy or local treatment like surgery is the priority.