Guardant Health presented results of largest study on ctDNA in colon cancer

Guardant Health (GH) presented results of the largest study to date evaluating circulating tumor DNA, ctDNA, in colon cancer prior to chemotherapy, demonstrating the ability of the Guardant Reveal test to stratify the risk of disease recurrence and overall survival, and thus inform treatment decisions after surgery. Data from the phase III trial of FOLFOX-based adjuvant chemotherapy involving over 2,000 patients with stage III colon cancer with median follow-up of 6.1 years were presented at the 2025 American Society for Clinical Oncology Annual Meeting. Results demonstrated that circulating tumor DNA detected in the bloodstream after cancer surgery and prior to the start of adjuvant therapy, using the Guardant Reveal test, is a strong predictor of the risk of disease recurrence and poorer survival, and suggest the potential for ctDNA testing to improve decision-making at a critical time point for post-operative chemotherapy. Specifically: Among patients with post-surgical ctDNA detected, 62.6% had the cancer return within 3 years, despite having had adjuvant chemotherapy, while only 15.4% of patients with undetectable ctDNA recurred in the same period. The level of ctDNA, or tumor fraction, showed promise in identifying individuals who are less likely to clear residual disease with adjuvant treatment.