Data presented at ESMO strengthened the case for circulating tumor DNA (ctDNA) to guide adjuvant treatment decisions. Roche reported a phase 3 analysis showing adjuvant atezolizumab provided a survival benefit in a ctDNA‑positive subset of bladder cancer patients, while broader ESMO sessions highlighted ctDNA‑guided trials in bladder and colon cancer that are shaping regulatory and commercial strategies. Researchers and firms including Natera, Roche and academic consortia discussed how ctDNA assays can stratify recurrence risk and de‑escalate or escalate therapy after surgery. The findings support regulatory filings and reimbursement discussions for ctDNA diagnostics and foreshadow broader use of liquid biopsies to personalize post‑surgical oncology care.