Guardant Health Publishes Largest ctDNA Study for Colon Cancer

Guardant Health announced publication of the largest study to date evaluating circulating tumor DNA for MRD detection in patients with resected stage III colon cancer after surgery and before adjuvant chemotherapy. The company said 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 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 six-fold higher rate of events if ctDNA was detected. The company said 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.