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Use a blood test after surgery to decide who gets chemotherapy: spare the negatives, and find something that actually works for the positives.
The idea is to make a post-operative ctDNA test such as Signatera the default decision tool for adjuvant therapy in stage II to III colon cancer, sparing ctDNA-negative patients chemotherapy and escalating positives to FOLFOX with or without a biology-matched agent. DYNAMIC showed that ctDNA-negative stage II patients can safely omit chemotherapy, while ALTAIR within CIRCULATE-Japan showed that late-line trifluridine and tipiracil does not help positives. The rationale is that post-operative ctDNA predicts recurrence far more strongly than any clinicopathological feature. Being tested at scale in CIRCULATE-US and COBRA-style platforms, it addresses the bottlenecks of dormant cells and minimal residual disease and of metastasis being studied last.
The blood test stratifies risk far better than stage or pathology. It supports treating ctDNA-positive patients and suggests ctDNA-negative patients gain little from chemotherapy, but because treatment was not randomised the de-escalation claim needs the randomised trials that are now under way.
For stage II colon cancer, where most patients are cured by surgery alone, a blood test can identify the minority who benefit from chemotherapy and spare everyone else its side effects. It does not yet prove that treating ctDNA-positive patients improves survival compared with not treating them.
Shares GALAXY: tumour DNA in blood four weeks after bowel cancer surgery predicts relapse tenfold, DYNAMIC: a blood test safely halved chemotherapy use after surgery for stage II colon cancer, CIRCULATE-Japan (GALAXY / VEGA / ALTAIR), DYNAMIC.
Shares Formally qualify tumour-DNA blood tests as a surrogate endpoint for adjuvant trials, DYNAMIC: a blood test safely halved chemotherapy use after surgery for stage II colon cancer, DYNAMIC, Signatera.
Shares Take ctDNA-guided de-escalation beyond stage II, and stop escalating on a positive result until a trial says it helps, DYNAMIC: a blood test safely halved chemotherapy use after surgery for stage II colon cancer, DYNAMIC, Signatera.
Shares CIRCULATE-Japan (GALAXY / VEGA / ALTAIR), DYNAMIC, Metastasis is understood least and studied last, Dormant cells and minimal residual disease.
Shares CIRCULATE-Japan (GALAXY / VEGA / ALTAIR), DYNAMIC, Diagnostics roadmap: stains → gene panels → blood tests that decide treatment, Dormant cells and minimal residual disease.
Shares DYNAMIC, Signatera, Dormant cells and minimal residual disease, Minimal / molecular residual disease (MRD).
Shares CIRCULATE-Japan (GALAXY / VEGA / ALTAIR), DYNAMIC, Signatera, Minimal / molecular residual disease (MRD).
Shares CIRCULATE-Japan (GALAXY / VEGA / ALTAIR), DYNAMIC, Signatera, ctDNA tests roadmap: from a curiosity in plasma to blood tests that decide treatment.