In neoadjuvant settings, ctDNA monitoring allows for real-time therapy adjustment. Data from the iSpy platform shows 80% of hormone-positive patients clear ctDNA with half the chemotherapy, enabling de-escalation, while the remaining 20% can be identified for escalated treatment.

A key conceptual shift is viewing ctDNA not as a statistical risk marker, but as direct detection of molecular residual disease (MRD). This framing, similar to how a CT scan identifies metastases, explains its high positive predictive value and justifies its use in making critical treatment decisions.

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.

A positive ctDNA test indicating minimal residual disease is strongly linked to recurrence. This expert argues clinicians have an obligation to act on this information, even without definitive guidelines. Framing inaction as unacceptable challenges the passive "wait-and-see" approach.

In neoadjuvant therapy, a patient's long-term outcome is better predicted by stopping tumor DNA shedding (ctDNA clearance) than by achieving pathologic complete response (pCR), the traditional gold standard. This redefines what constitutes a successful treatment response before surgery.

While promising, current ctDNA technology is not robust enough to justify stopping effective neoadjuvant systemic therapy in bladder cancer, even if a patient becomes ctDNA negative. Experts argue against using it to de-escalate treatment outside of a clinical trial due to the risk of undertreating a lethal disease.

Experts warn against over-interpreting a single negative ctDNA test after surgery, clarifying that these patients still face a significant 25-30% risk of recurrence. The biomarker's true prognostic power comes from serial testing that shows a patient remains persistently negative over time.

The interpretation of ctDNA is context-dependent. Unlike in the adjuvant setting, in the neoadjuvant setting, remaining ctDNA positive post-treatment signifies that the current therapy has failed. These high-risk patients need a different therapeutic approach, not an extension of the ineffective one.

When a patient becomes ctDNA positive during surveillance after completing adjuvant therapy, the optimal next step is not immediate systemic chemotherapy. Clinicians should instead initiate intensive imaging (e.g., CT, PET) to identify a potential radiographic recurrence, which may be isolated and resectable.