AT the American Association for Cancer Research (AACR) Annual Meeting 2025 in Chicago, new data revealed that a liquid biopsy using circulating tumor DNA (ctDNA) could detect colorectal cancer recurrence significantly earlier than imaging, with ctDNA signals appearing up to 416 days before clinical detection. These interim results from the ongoing VICTORI study demonstrate how personalized blood-based assays may transform post-surgical monitoring in patients with resectable colorectal cancer.
Colorectal cancer recurrence often evades early detection because ctDNA levels in blood can be extremely low. However, the ultrasensitive assay used in this study, tailored to each patient’s tumor-specific mutations, detected ctDNA at levels as low as 2 parts per million. Researchers followed 71 patients with stage 1 to 4 resectable colorectal cancer using liquid biopsies before and after surgery, with post-surgical samples taken biweekly for two months and quarterly thereafter.
Among 65 patients evaluable for clinical outcomes, 23 experienced recurrence. Of these, 87% were ctDNA-positive during the critical eight-week post-surgery period, a window typically used for initiating adjuvant chemotherapy. All patients with recurrence had detectable ctDNA well before imaging revealed relapse, with a median lead time of 198 days. Notably, ctDNA was able to flag even difficult-to-detect metastatic sites, such as the lung.
Higher ctDNA levels at first detection were associated with shorter time to clinical relapse. According to lead investigator Dr. Jonathan Loree of BC Cancer, these findings could help identify which patients may benefit from additional therapy—or be spared unnecessary treatment. Co-investigator Emma Titmuss noted that four weeks post-surgery appears to be the ideal timepoint for clinically informative ctDNA testing.
Although this was an observational study with no treatment changes based on ctDNA findings, the authors emphasize the importance of future randomized trials to define the clinical utility of ctDNA-guided care. The study continues to enroll patients to refine these early insights.
Reference: Titmuss E, Loree J. A Liquid Biopsy-based Assay Could Detect Recurrence Prior to Imaging in Patients With Resectable Colorectal Cancer. 2025. Available at: https://aacr.ent.box.com/s/ss6uy0qzbu378y7jnnguhjb2e2csko0l. Last accessed: 1 May 2025.
