Is the Signatera test (circulating tumor DNA test) effective for surveillance in an older adult patient with a history of bladder cancer, particularly those with high-grade or muscle-invasive disease?

Signatera ctDNA Testing for Bladder Cancer Surveillance

The Signatera test shows strong promise for surveillance in older adults with high-grade or muscle-invasive bladder cancer, particularly after radical cystectomy, where it demonstrates 100% sensitivity and negative predictive value for detecting recurrence, potentially allowing less intensive imaging surveillance in patients with persistently undetectable ctDNA. 1, 2

Evidence for ctDNA Testing in Muscle-Invasive Bladder Cancer

Post-Cystectomy Surveillance Performance

The strongest evidence comes from recent real-world studies of the Signatera tumor-informed ctDNA assay:

• Detectable ctDNA after radical cystectomy is strongly prognostic: Patients with detectable ctDNA in the postoperative molecular residual disease (MRD) window had significantly shorter disease-free survival (hazard ratio 6.93, p < 0.001), and during surveillance windows (hazard ratio 23.02, p < 0.001) 1

• Exceptional diagnostic accuracy: In 94 patients post-cystectomy, ctDNA demonstrated 100% sensitivity and 100% negative predictive value for detecting recurrence, with 91.8% specificity and 84.5% positive predictive value when compared to imaging 2

• Independent prognostic factor: Detectable ctDNA was the only risk factor independently associated with shorter disease-free survival across pre-operative (p = 0.045), MRD (p = 0.002), and surveillance (p < 0.001) windows 1

Clinical Utility for Treatment Decisions

Patients with undetectable ctDNA after surgery did not appear to benefit from adjuvant chemotherapy (p = 0.34), suggesting ctDNA may help identify who truly needs additional systemic therapy. 1

This predictive value is critical for older adults, where avoiding unnecessary chemotherapy toxicity is paramount for quality of life.

Application in Non-Muscle-Invasive Bladder Cancer

Emerging Role in High-Risk NMIBC

For high-grade non-muscle-invasive disease, early data suggest potential utility:

• Early detection of progression: ctDNA positivity detected locally advanced disease earlier than standard surveillance, prompting timely initiation of systemic therapy 3

• Detection rate: ctDNA was detected in 35% of NMIBC patients, particularly useful in BCG-unresponsive disease where it detected early recurrence and prompted escalation to radical cystectomy 3

However, the role in NMIBC remains less well-defined than in muscle-invasive disease, and prospective validation is needed. 3

Comparison to Standard Surveillance Methods

Limitations of Current Approaches

Standard surveillance relies on cystoscopy, cytology, and imaging, each with significant limitations:

• Urine cytology: High specificity but low sensitivity for low-grade tumors (29% sensitivity even with cystoscopy) 4

• Imaging surveillance: Current guidelines recommend intensive post-cystectomy imaging (CT chest/abdomen/pelvis every 3-6 months for 2 years, then annually) 4, but this exposes patients to repeated radiation and contrast without molecular-level sensitivity

• Cystoscopy: Remains gold standard for bladder visualization but cannot detect distant micrometastatic disease 4

ctDNA Advantages

ctDNA offers systemic disease detection capability that cystoscopy cannot provide, while avoiding the radiation exposure and cost of repeated cross-sectional imaging. 2

Practical Implementation Algorithm

For Muscle-Invasive Disease Post-Cystectomy:

1. Baseline ctDNA testing: Obtain pre-operative sample for tumor-informed assay development 1

2. MRD window (4-12 weeks post-op):

   • If ctDNA detectable → High-risk for recurrence, strongly consider adjuvant chemotherapy if fit 1
   • If ctDNA undetectable → Lower intensity surveillance may be appropriate 2

3. Surveillance protocol modification:

   • Persistently undetectable ctDNA: Consider reducing imaging frequency below standard guidelines (every 6-12 months rather than 3-6 months), given 100% NPV 2
   • Detectable ctDNA: Immediate comprehensive imaging regardless of schedule, as recurrence is highly likely 1, 2

For High-Grade NMIBC:

1. Consider ctDNA testing in BCG-unresponsive disease or when deciding between bladder preservation vs. cystectomy 3

2. Positive ctDNA may indicate occult muscle-invasive disease or high progression risk, warranting restaging TURBT or consideration of early cystectomy 3

Critical Caveats

Age-Related Considerations

In older adults, the decision to use ctDNA testing must weigh the patient's fitness for intervention against the test's prognostic information:

• If the patient is not a candidate for chemotherapy or cystectomy due to comorbidities, ctDNA results may not change management 1

• However, ctDNA can still guide palliative vs. curative intent and inform discussions about quality of life vs. treatment burden 1

Test Limitations

• Tumor-informed assay requirement: Signatera requires adequate tumor tissue from TURBT or cystectomy specimen for personalized assay design 1, 2, 3

• Not a replacement for cystoscopy in NMIBC: Standard guidelines explicitly state urinary biomarkers should not replace cystoscopic evaluation for NMIBC surveillance 4

• Cost considerations: Commercial ctDNA testing is expensive, and cost-effectiveness data in bladder cancer surveillance are limited 5

Guideline Context

Current guidelines do not yet incorporate ctDNA testing, as the evidence is recent (2024-2025) 4. The USPSTF found inadequate evidence for screening asymptomatic adults 4, but this addresses primary screening, not surveillance in known cancer patients.

Bottom Line for Clinical Practice

For older adults with muscle-invasive bladder cancer post-cystectomy, Signatera ctDNA testing is highly effective for surveillance and should be strongly considered to guide adjuvant therapy decisions and potentially reduce imaging burden in ctDNA-negative patients. 1, 2

For high-grade NMIBC, ctDNA testing is emerging as a useful adjunct in BCG-unresponsive disease but should not replace standard cystoscopic surveillance. 4, 3

The exceptional negative predictive value (100%) means persistently undetectable ctDNA provides strong reassurance that intensive surveillance may be safely de-escalated, improving quality of life for older adults while maintaining oncologic safety. 2