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‹ Tue · 2 Jun 2026
Early cancer detection or prevention

Chemotherapy for patients with circulating tumour DNA positive, stage II colon cancer (CIRCULATE) - an AIO / ABCSG trial

Blood-based tumor DNA test identifies stage II colon cancer patients who benefit most from chemotherapy, pointing toward personalized treatment for traditionally undertreated subgroups.

The CIRCULATE trial confirms that postoperative ctDNA positivity is a powerful prognostic marker in stage II colon cancer (HR 4.28 for DFS), and per-protocol analysis provides the strongest prospective signal yet that ctDNA-guided adjuvant chemotherapy dramatically reduces recurrence (HR 0.23) — though the small CHEMO arm (n=26) and premature closure prevent definitive conclusions. This trial adds to a growing evidence base that ctDNA-positive stage II colon cancer should receive adjuvant therapy, potentially changing practice for a subgroup traditionally undertreated.

What the study was

Study design
RCT (2:1 ctDNA-positive to CHEMO vs OBS); trial ended early due to funding expiry
Population
Stage II (UICC II) pMMR/MSS colon cancer patients; ctDNA-positive subgroup randomized to chemotherapy vs observation
Sample size
2126
Category
Early Detection
Maturity
Validated
Journal
Annals of Oncology

Why it surfaced

RCT design (albeit underpowered due to early closure) provides the highest feasible evidence level for ctDNA-guided adjuvant decision-making in stage II colon cancer; per-protocol HR 0.23 is a very large effect size; Ann Oncol is a top oncology journal; ctDNA testing for stage II CRC is already in clinical guidelines discussions and this data strongly supports it.

A plain-language summary of published research — not medical advice. Talk to a clinician about your own care.