When is circulating tumor DNA (ctDNA) testing indicated in the management of bladder cancer, and how should its results be interpreted relative to cystoscopy, imaging, and urine cytology?

Circulating Tumor DNA (ctDNA) in Bladder Cancer Management

Current Guideline Position

ctDNA testing is not currently recommended for routine surveillance in bladder cancer, but emerging evidence suggests it may have a future role in detecting recurrence after radical cystectomy, particularly for risk stratification and potentially reducing imaging intensity in patients with persistently undetectable ctDNA. 1

The 2024 AUA/ASCO/SUO guidelines explicitly state that while some evidence suggests a potential role for ctDNA in detecting recurrence and progression following radical cystectomy, future studies are needed to further define its role for surveillance. 1 Current urinary markers have limited utility in routine monitoring after radical cystectomy due to false positive rates. 2

Standard Surveillance Remains the Gold Standard

For Non-Muscle-Invasive Bladder Cancer (NMIBC)

• Cystoscopy every 3-6 months for the first 2 years for high-grade disease, with concurrent urine cytology at each visit 2
• Upper tract imaging every 1-2 years using CT urography or MRI urography 1
• Urinary biomarkers (FISH, NMP22) may be considered as adjuncts (Category 2B) but should never replace cystoscopy 2, 3

For Muscle-Invasive Bladder Cancer (MIBC) Post-Cystectomy

• Cross-sectional imaging (CT chest/abdomen/pelvis) at regular intervals based on risk stratification 1
• Urine cytology remains standard despite interpretation difficulties after urinary diversion 2
• Cystoscopy is not applicable after cystectomy, making ctDNA potentially more valuable in this population 4

Emerging Role of ctDNA: When to Consider

Post-Radical Cystectomy Surveillance

The highest quality and most recent evidence supports ctDNA use specifically after radical cystectomy for muscle-invasive disease. A 2025 prospective study of 94 patients demonstrated that ctDNA (Signatera™) achieved 100% sensitivity and negative predictive value, with 91.8% specificity for detecting recurrence compared to imaging. 4

Clinical algorithm for post-cystectomy ctDNA integration:

• Obtain baseline ctDNA testing 4-6 weeks after radical cystectomy 4, 5
• If ctDNA persistently undetectable: Consider de-escalating imaging frequency from standard protocols, as these patients have extremely low recurrence risk (NPV 100%) 4
• If ctDNA becomes detectable: Immediately intensify surveillance with cross-sectional imaging, as this predicts recurrence with 84.5% positive predictive value 4
• Serial monitoring every 3-4 months during the first 2 years when recurrence risk is highest 5

Prognostic Value in MIBC

• Detectable ctDNA before cystectomy is associated with worse overall survival and disease recurrence 6
• Persistent ctDNA after neoadjuvant chemotherapy correlates with residual tumor on surgical pathology 6
• Dynamic changes in ctDNA status between baseline and 4 months post-cystectomy significantly predict patient outcomes (HR 30.865 at 12 months) 5

Limited Role in NMIBC

ctDNA has minimal established utility in non-muscle-invasive disease management. A 2025 real-world study of 23 NMIBC patients found ctDNA detectable in only 35% of cases, though it did facilitate early detection of progression in select high-risk patients with BCG-unresponsive disease. 7

Specific scenarios where ctDNA may inform NMIBC management:

• BCG-unresponsive high-grade disease: ctDNA positivity may prompt earlier cystectomy rather than continued intravesical therapy 7
• Suspected occult muscle invasion: Baseline ctDNA positivity may trigger earlier reimaging that reveals locally advanced disease 7

Critical Limitations and Pitfalls

What ctDNA Cannot Replace

• Never use ctDNA instead of cystoscopy for bladder surveillance in patients with intact bladders 1, 2, 3
• Do not use for initial diagnosis of bladder cancer—cystoscopy with biopsy remains mandatory 1, 3
• Not validated for screening asymptomatic populations 3

Technical Considerations

• Tumor-informed assays (Signatera™) require initial tumor tissue sequencing, limiting applicability if tissue is unavailable 4, 7
• Tumor-agnostic approaches (targeting TERT c.1-124C>T, ATM mutations) avoid this limitation but may have lower sensitivity 5
• False positives occur in 8-16% of cases, potentially leading to unnecessary imaging and anxiety 4

Population-Specific Limitations

• Low sensitivity in early-stage disease: ctDNA detection rates are significantly lower in Ta/T1 disease compared to muscle-invasive disease 6, 7
• Urine tumor DNA (utDNA) outperforms ctDNA for bladder-confined disease, with 91% sensitivity and 96% specificity 6

Practical Implementation Strategy

For patients post-radical cystectomy (where evidence is strongest):

1. Establish baseline ctDNA status 4-6 weeks post-operatively using tumor-informed assay 4

2. Risk-stratify based on initial result:

   • Undetectable ctDNA: Consider imaging every 6-12 months instead of standard 3-6 months 4
   • Detectable ctDNA: Maintain intensive imaging every 3 months and consider systemic therapy 4, 5

3. Serial monitoring schedule:

   • Every 3 months for first 2 years 5
   • Every 6 months for years 3-5 5
   • Coordinate with imaging studies 4

4. Action on ctDNA conversion:

   • Negative to positive: Obtain immediate cross-sectional imaging regardless of scheduled interval 4, 7
   • Positive to negative: Continue surveillance but may indicate treatment response 5

For NMIBC patients: ctDNA remains investigational and should not alter standard cystoscopic surveillance protocols outside clinical trials. 1, 7

Future Directions

The 2024 AUA/ASCO/SUO guidelines acknowledge that optimal surveillance strategies after definitive treatment remain undefined, and ctDNA represents a promising area requiring further study. 1 The National Comprehensive Cancer Network is expected to integrate molecular analysis recommendations as evidence matures. 8 Prospective trials are needed to validate whether ctDNA-guided surveillance protocols improve mortality, morbidity, or quality of life compared to standard imaging-based approaches. 4, 8