Validation of a Circulating Tumor DNA Blood Test in Muscle-Invasive Bladder and Upper Tract Urothelial Cancer

This prospective observational study evaluates a blood-based circulating tumor DNA (ctDNA) test in patients with muscle-invasive bladder cancer or upper tract urothelial cancer. ctDNA consists of small fragments of tumor DNA that can sometimes be detected in the blood. In this study, DNA from tumor tissue obtained during routine diagnostic or surgical procedures will be analyzed to identify tumor-specific mutations. Blood samples collected during routine clinical care will then be tested to determine whether the same mutations can be detected in plasma ctDNA. The main purpose is to assess how well the internally developed ctDNA assay detects tumor-specific mutations compared with tumor tissue sequencing. The study will also explore whether ctDNA results after treatment are associated with recurrence or remission during two years of follow-up, and whether changes in ctDNA levels during treatment are associated with pathological response. This study does not assign participants to a treatment and does not require additional blood draws beyond routine care. Treating physicians will remain blinded to ctDNA results during the study, so the test results will not influence clinical decisions.