New Liquid Biopsy Assay Promises Early Detection of Colorectal Cancer Recurrence

Recent findings from the VICTORI study, presented at the American Association for Cancer Research Annual Meeting 2025, indicate that a highly sensitive liquid biopsy assay can identify signs of recurrence in patients with resectable colorectal cancer (CRC) before they are detectable through conventional imaging methods.

The study emphasizes the significance of circulating tumor DNA (ctDNA) as a biomarker for early recurrence detection, which is crucial considering that traces of ctDNA can be extremely low in the bloodstream. If identified early, these blood-based biomarkers can greatly influence clinical decision-making regarding patient care.

According to the interim results, the ctDNA-based assay showed promising prognostic capabilities within a month following surgical intervention. The investigation included 71 patients diagnosed with resectable CRC, comprising individuals with varying stages of the disease, including 52 patients with stages 1 to 3 and 19 patients with stage 4.

Researchers developed a customized panel of up to 1,800 somatic variants derived from each patient's tumor tissue. Liquid biopsies were conducted prior to surgery, biweekly for eight weeks post-surgery, and quarterly for up to three years, utilizing the NeXT Personal assay for analysis.

Of the 33 patients with treatment-naïve disease exceeding stage 1, all exhibited detectable ctDNA prior to surgical procedures. Among the 65 patients assessed for clinical outcomes, 23 experienced a recurrence of the disease. Notably, a significant majority (87%) of these patients tested positive for ctDNA within the critical eight-week post-surgical window when adjuvant chemotherapy typically begins.

Alarmingly, all patients who later faced clinical recurrence were ctDNA-positive well before their recurrence was confirmed through imaging--by a median of 198 days earlier. This included instances of metastasis to challenging sites, such as the lungs, with one patient's ctDNA indicating recurrence a staggering 416 days prior to clinical confirmation.

The study indicated that ctDNA levels could be detected at concentrations as low as 2 parts per million (ppm), with a median detection level of 24.4 ppm and the highest recorded at 111,120 ppm. Higher levels of ctDNA at initial detection correlated with shorter periods until clinical relapse.

Researchers suggested that utilizing ctDNA assessments two weeks post-surgery might be too soon, as residual normal cell-free DNA can obscure the detection of ctDNA. They propose that a four-week interval might provide a more clinically relevant timeframe for sampling ctDNA and informing treatment decisions.

The ongoing study aims to enroll additional patients to enhance the precision of its findings and guide future prospective studies that could integrate ctDNA analysis into routine clinical management. However, the study's observational nature limits its capacity to implement interventions based on ctDNA detection, underscoring the necessity for randomized trials to ascertain the most effective applications of this technology in patient care.