Abstract Detection of circulating tumor DNA (ctDNA) postoperatively is prognostic for recurrence for patients with stage III colon cancer. Those with sustained undetectable ctDNA will likely be cured. Eradication of minimal residual disease (per ctDNA clearance) with chemotherapy did not occur in most ctDNA-positive patients and led to eventual disease relapse. See related article by Henriksen et al., p. 507