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ctDNA Guided Therapy — SCE Medical Oncology MCQ

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HardGI CancersctDNA Guided TherapySCE Medical Oncology

A 65-year-old woman with stage II colon cancer (pT4a N0 M0, MSS) undergoes right hemicolectomy. She asks about the role of ctDNA to guide adjuvant chemotherapy decisions. What does current evidence (DYNAMIC trial) suggest?

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Correct answer: C — Postoperative ctDNA positivity identifies patients at high risk of recurrence who benefit from adjuvant chemotherapy; ctDNA-negative patients may safely omit chemotherapy

The Australian DYNAMIC trial (Tie et al NEJM 2022) demonstrated that ctDNA-guided adjuvant therapy in stage II colon cancer was non-inferior to standard clinicopathological risk-guided management, while reducing the proportion of patients receiving unnecessary chemotherapy by approximately 50%. ctDNA-positive patients (detectable MRD) had a 10-fold higher recurrence risk and benefited from adjuvant fluoropyrimidine ± oxaliplatin. This represents a paradigm shift toward molecular minimal residual disease-guided treatment decisions.

Reference: ESMO 2024 Early Colorectal Cancer Guidelines; DYNAMIC Tie et al NEJM 2022