On February 2, 2026 Guardant Health, Inc. (Nasdaq: GH), a leading precision oncology company and research collaborators at Mayo Clinic and the Alliance for Clinical Trials in Oncology reported publication of the largest study to date evaluating circulating tumor DNA (ctDNA) for MRD 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.

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Researchers found that about 20 percent of patients in the phase III trial, which was presented at the 2025 American Society for Clinical Oncology (ASCO) (Free ASCO Whitepaper) 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.

"The data suggest that not only the presence of ctDNA, but the amount of ctDNA, as identified by Guardant Reveal may help refine risk beyond standard TNM staging, and could be used to guide adjuvant treatment and surveillance decisions," said Frank Sinicrope, MD, professor of oncology and medicine at Mayo Clinic and principal investigator for the study. "ctDNA testing after surgery improves the accuracy of estimating a patient’s risk of cancer recurrence, enabling more tailored recommendations for adjuvant chemotherapy and follow-up monitoring. It also identifies high risk patients who are likely to recur despite standard treatment, and who may benefit from alternative therapeutic approaches."

"This large study adds to growing evidence that ctDNA testing with Guardant Reveal after surgery helps answer the question patients care about most: Am I really cancer-free?" said Dr. Craig Eagle, Guardant Health Chief Medical Officer. "Personalizing care after surgery is essential as clinicians and patients decide what comes next. Guardant Reveal fits easily into routine practice and provides timely, actionable insight—helping identify patients at high risk while sparing others unnecessary treatment and anxiety."

Today’s announcement is the latest data reinforcing the clinical utility of Guardant Reveal in molecular residual disease and beyond. Guardant recently expanded Reveal to support late-stage therapy response monitoring, enabling ctDNA-based assessment of treatment effectiveness across solid tumors. This adds to evidence from early-stage breast cancer publications that Reveal’s tissue-free approach can identify patients at elevated risk of recurrence and support more personalized care.

(Press release, Guardant Health, FEB 2, 2026, View Source [SID1234662411])