Serial ctDNA Detects More Colorectal Cancer Recurrences: Gut | October 2026

What Did the Study Find?

INTERCEPT prospectively followed patients with stage II–IV colorectal cancer treated with curative intent, using a personalised, tissue-informed circulating tumour DNA assay during routine surveillance. The published abstract does not report the cohort size, and there was no randomised ctDNA-negative control strategy.

Longitudinal testing increased recurrence-detection sensitivity from 48.5% with a single timepoint to 79.9% with repeated sampling. When ctDNA became detectable, clinicians used MRI or PET imaging significantly more frequently. However, 26% of positive tests already coincided with radiographically visible disease, reducing the proportion in whom ctDNA provided true molecular lead time. MRD positivity remained strongly prognostic beyond 12 months, and MRD-positive stage II–III disease carried greater recurrence risk than MRD-negative stage IV disease. Adjuvant therapy produced limited durable benefit in stage IV patients irrespective of MRD status. Gut

Why Does It Matter?

Serial testing is clearly superior to a one-off postoperative sample for risk stratification. Nevertheless, this observational study does not prove that acting on an isolated positive result improves survival or justify empirically escalating systemic therapy without radiographic disease.

GastroAGI Takeaway

Use serial ctDNA as a high-risk signal that should trigger focused evaluation—not yet as a stand-alone mandate to start or intensify treatment.