Trial Tested ctDNA for Rectal Cancer Treatment
Researchers used a blood-based assay to guide surgical decisions for node-negative rectal cancer patients in Canada.
Updated on Oct. 11, 2026 in Cancer
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The CO.28 clinical trial evaluated whether circulating tumor DNA (ctDNA) detection could effectively guide treatment decisions for node-negative rectal cancer patients. Results showed that testing blood samples after chemotherapy helped determine the necessity of total mesorectal excision.
Why it matters
This study aimed to reduce invasive surgeries by using blood-based ctDNA markers to identify which patients truly require total mesorectal excision. Refining these treatment protocols could significantly change clinical management for those with localized rectal cancer.
The Guardant Reveal assay analyzed 20,000 DNA regions to detect ctDNA in 91.4% of trial participants. Post-chemotherapy ctDNA detection fell to 8.7%, with a 90.5% three-year recurrence-free rate for ctDNA-negative patients.
The players
Canadian Cancer Trials Group
This organization facilitates large-scale oncology research and clinical trials across Canada.
The details
Researchers collected blood samples before and after three months of chemotherapy followed by transanal endoscopic surgery. All four patients who maintained detectable ctDNA after chemotherapy were recommended for further total mesorectal excision to address potential recurrence.
Timeline
October 2, 2026: Study results were published in JCO Precision Oncology.
Post-chemotherapy: ctDNA detection rates dropped to 8.7%.
Three years post-enrollment: Recurrence-free rates were calculated for study participants.
The Big Picture
This research follows the standard set by the Canadian Cancer Trials Group CO.28 trial in modern oncology. It highlights a shift toward using liquid biopsies to refine surgical necessity, moving away from universal invasive procedures.
This research could eventually offer patients less invasive treatment options by identifying who can safely avoid total mesorectal excision. It highlights the growing potential of blood-based assays to reduce the physical burden of cancer therapy.
The takeaway
Using ctDNA testing to guide surgery may help physicians tailor rectal cancer treatments to individual patient needs. This advancement suggests a future where blood tests play a greater role in reducing unnecessary surgical procedures.
What happens next
Researchers plan to initiate a phase 3 trial to compare the ctDNA-guided approach against standard chemoradiation followed by local excision.
Further reading
For more information on current treatment standards, visit the Canada Cancer section.
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