Guardant Health, Inc. and research collaborators at Mayo Clinic and the Alliance for Clinical Trials in Oncology announced publication of the largest study to date evaluating circulating tumor DNA (ctDNA) forMRD detection in patients with resected stage III colon cancer after surgery and before adjuvant chemotherapy. Results of the study, published in the Journal of Clinical Oncology, show that detecting ctDNA with the Guardant Reveal®? blood test better predicts recurrence and overall survival than standard staging.
Researchers found that about 20% of patients in the phase III trial, which was presented at the 2025 American Society for Clinical Oncology (ASCO) Annual Meeting, involving more than 2,000 patients still had detectable ctDNA in their blood after surgery. Guardant Reveal identified patients at a four-to-six-fold higher rate of disease recurrence or reduced survival. Even patients with smaller tumors or fewer affected lymph nodes found as part of traditional staging had an over 6-fold higher rate of events if ctDNA was detected.
The findings support the integration of tissue-free ctDNA testing into routine postoperative management to better identify patients at high risk of recurrence who may benefit from intensified surveillance or alternative adjuvant strategies. Measuring the amount of cancer DNA in the blood, a marker known as tumor fraction, further distinguished those at the highest risk of early recurrence and worse survival. This additional layer of information may help clinicians prioritize patients who need the most intensive surveillance or consideration of alternative therapies.
