Circulating tumor DNA (ctDNA) for molecular residual disease tracking could help identify patients with colorectal cancer and liver metastases who are most likely to benefit from adjuvant chemotherapy after surgery, according to findings from an overall survival analysis of the phase II GALAXY study presented at the ESMO Gastrointestinal Cancers Congress 2026 (Abstract 80).
“These findings are promising because they suggest ctDNA could help... identify which patients are most likely to benefit from chemotherapy after surgery, while potentially sparing others unnecessary treatment," stated Per Pfeiffer, MD, PhD, Professor of Oncology at Odense University Hospital in Denmark, who was not involved in the study. “However, the evidence is not yet strong enough for ctDNA to be used routinely outside clinical trials, and further studies, preferably randomized, are needed before this approach becomes standard practice.”
Background and Study Methods
The GALAXY study was an arm of the CIRCULATE-Japan trial that analyzed pre- and postsurgical ctDNA in patients with stage II–IV resectable colorectal cancer to assess the efficacy of adjuvant chemotherapy.
“Only around 1 in 10 patients is cured by adjuvant therapy, yet almost all patients experience treatment-related side effects. We hope ctDNA can help better identify which patients are most likely to benefit from adjuvant chemotherapy,” Dr. Pfeiffer said.
The researchers conducted an updated overall survival analysis of the GALAXY study to assess the predictive value of ctDNA-based molecular residual disease testing for determining adjuvant chemotherapy benefit in patients with resected colorectal liver metastases. The updated analysis included 298 patients with available ctDNA results 2 to 10 weeks postsurgery, tested with a Signatera tumor-informed assay. They separately analyzed patients undergoing upfront surgery (n = 191) and those receiving neoadjuvant chemotherapy (n = 107).
Key Findings
In the upfront surgery cohort, MRD positivity was reported in 63 of 129 evaluable patients and was associated with significantly worse disease-free survival (hazard ratio = 4.15; 95% confidence interval = 2.70–6.38).
Four years after upfront surgery, the overall survival rate was 65% in patients who received adjuvant chemotherapy vs 33% in those who did not. The 4-year disease-free survival rate was 38% with adjuvant chemotherapy vs 7% without.
Adjuvant chemotherapy treatment was associated with a lower risk of cancer recurrence and death.
DISCLOSURES: CIRCULATE-Japan receives financial support from the Japan Agency for Medical Research and Development and the National Cancer Center Research and Development Fund. For full disclosures of the study authors, visit oncologypro.esmo.org.
