A personalized blood test measuring circulating tumor DNA (ctDNA) can identify colorectal cancer patients who benefit most from adjuvant chemotherapy after liver metastasis surgery. According to the Phase II GALAXY study presented at the ESMO Gastrointestinal Cancers Congress 2026, patients with detectable ctDNA after surgery saw overall survival rates of 65% with chemotherapy, compared to 33% without it.
How ctDNA Testing Influences Post-Surgical Care
The GALAXY study, led by researchers from Hyogo Medical University and the University of Oxford, tracked 298 patients to determine if molecular markers could predict recurrence. For those who underwent upfront surgery, the presence of ctDNA was a critical indicator of risk. Patients with detectable ctDNA faced more than four times the risk of cancer recurrence and more than nine times the risk of death compared to those who tested negative.
The data suggests a clear path for treatment selection. Among the 191 patients who underwent upfront surgery, those with detectable ctDNA experienced a 93% reduction in the risk of recurrence when treated with adjuvant chemotherapy. Conversely, patients without detectable ctDNA showed favorable long-term outcomes regardless of whether they received subsequent chemotherapy.
Colorectal cancer is the third most common cancer worldwide and the second leading cause of cancer death, with the liver serving as the most common site of metastatic spread.
Why Current Treatment Protocols May Change
Current clinical practice often involves administering chemotherapy to patients following surgery to address potential microscopic cancer cells. However, Per Pfeiffer, MD, PhD, professor of oncology at Odense University Hospital, notes that only about 1 in 10 patients is cured by this adjuvant therapy, even as nearly all experience treatment-related side effects.
The study highlights a distinct difference in outcomes based on when surgery occurs. In that specific subgroup, additional post-surgical chemotherapy provided no observable benefit, regardless of ctDNA status.
Moving Toward Precision Oncology
The potential for ctDNA to spare patients from unnecessary, toxic treatments is a primary driver of this research. By identifying which individuals are unlikely to benefit from chemotherapy, clinicians may soon be able to personalize care plans more effectively.
Despite these findings, researchers emphasize that this diagnostic approach is not yet ready for standard clinical use. According to Dr. Pfeiffer, further randomized studies are required to validate these results before ctDNA testing can be integrated into routine oncology practice outside of clinical trials.
Frequently Asked Questions
- What is ctDNA?
Circulating tumor DNA (ctDNA) refers to small fragments of DNA released by tumor cells into the bloodstream, which can be detected via a specialized blood test. - Can ctDNA testing replace chemotherapy?
Not currently. According to researchers, the evidence is not yet strong enough for routine use, and further randomized clinical trials are necessary. - Who should consider this test?
The study focused on patients with colorectal cancer that has spread to the liver. It is currently being evaluated within the context of clinical research trials.
If you are currently managing a cancer diagnosis, ask your oncologist about active clinical trials in your area. Participating in research is often the only way to access emerging diagnostic technologies like personalized ctDNA monitoring.
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