Researchers presented a study at the ASCO Genitourinary Cancers Symposium 2026 examining whether circulating tumor DNA (ctDNA) can help guide treatment decisions for patients with muscle-invasive bladder cancer. The research was part of the RETAIN-2 trial and focused on patients who received chemoimmunotherapy with Nivolumab instead of immediately undergoing bladder removal surgery (cystectomy).
The study found that ctDNA in the blood can help predict whether the cancer will spread to other organs. Patients whose ctDNA tests were negative after treatment had good outcomes, with about 80% remaining free from metastasis two years later. However, ctDNA was not effective at detecting cancer that returned only in the bladder. Most patients who developed local recurrences still had negative ctDNA tests.
These findings suggest ctDNA can help doctors decide when it may be safe to avoid major surgery and preserve the bladder if patients respond well to treatment. Still, regular monitoring of the bladder using tests such as cystoscopy is necessary to detect local recurrence. Researchers are now planning the RETAIN-3 trial to further study how ctDNA can guide treatment decisions.