Ultrasensitive Blood Test Transforms Colorectal Cancer Risk Prediction

MORRISVILLE, N.C. – January 07, 2026 – New data presented this week from one of the largest real-world studies on colorectal cancer has unveiled the profound prognostic power of an ultrasensitive blood test, potentially setting a new standard for how clinicians manage the disease after surgery. The findings, presented at the 2026 American Society for Clinical Oncology (ASCO) Gastrointestinal Cancers Symposium, demonstrate that SAGA Diagnostics’ Pathlight assay can predict the likelihood of cancer recurrence with startling accuracy, identifying high-risk patients that less sensitive methods might miss.

The data comes from the CIrculating Tumour DNA (ctDNA) as a Prognostic and Predictive Marker in Colorectal CAncer (CITCCA) study, a multicenter, prospective trial conducted in collaboration with the prestigious Karolinska Institutet in Sweden. The results highlight a dramatic difference in outcomes between patients who test positive for trace amounts of cancer DNA in their blood post-treatment and those who do not, offering a clearer path forward for personalizing patient care.

The Power of Ultrasensitivity: Unpacking the CITCCA Data

The CITCCA study retrospectively analyzed blood samples from 377 patients with stage I–III colorectal cancer who had received standard-of-care treatment across seven Swedish medical centers. The goal was to determine if the presence of circulating tumor DNA (ctDNA)—tiny fragments of DNA shed by tumors into the bloodstream—could predict which patients would eventually relapse. The results were unequivocal.

Patients who were ctDNA-positive following their treatment had a staggering 38.5 times higher risk of their cancer returning compared to patients who were ctDNA-negative. This powerful predictive capability was consistent across cancer types, with a hazard ratio of 33.8 for colon cancer and an even more pronounced 93.5 for rectal cancer, a particularly challenging subset of the disease.

The long-term impact on patient outcomes was just as stark. The three-year recurrence-free interval (RFI)—the time from surgery until the cancer is first detected again—was approximately 90% for ctDNA-negative patients, suggesting their treatment was likely curative. In stark contrast, for ctDNA-positive patients, the three-year RFI plummeted to just 30%.

“The CITCCA study provides compelling prospective evidence that ctDNA is a powerful predictor of recurrence in patients with stage I–III colorectal cancer,” said Professor Anna Martling of the Karolinska Institutet and the study's principal investigator. “The striking difference in three-year recurrence-free interval between ctDNA-positive and ctDNA-negative patients highlights the clinical value of structural-variant-based ultrasensitive MRD detection.”

Crucially, the study underscored the importance of how you look for this residual disease. A remarkable 42.5% of the ctDNA-positive patients had cancer DNA levels below 100 parts per million (ppm), a range so low that it is only detectable by ultrasensitive assays like Pathlight. This finding suggests that a significant portion of patients at the highest risk of relapse would be misclassified as low-risk by less sensitive tests, potentially missing a critical window for intervention.

Redefining Treatment Pathways for Colorectal Cancer

The clinical implications of these findings are immense, promising to shift the paradigm from a one-size-fits-all approach to a highly personalized strategy. One of the most challenging decisions in early-stage colorectal cancer is whether to administer adjuvant chemotherapy (ACT) after surgery. While ACT can be lifesaving, it also carries significant toxicities and side effects. For many patients, it amounts to overtreatment.

The CITCCA data provides a powerful tool to refine this decision. The study showed that recurrence risk was markedly higher in ctDNA-positive patients who did not receive ACT, strongly suggesting that a positive test could be a clear signal to proceed with chemotherapy. Conversely, a negative test could give clinicians and patients greater confidence to forgo ACT, sparing them from unnecessary treatment.

“Tools like Pathlight have the potential to meaningfully improve how we risk-stratify patients and tailor treatment and follow-up strategies,” Professor Martling noted, emphasizing the test's role in guiding more precise clinical decisions.

Beyond adjuvant therapy, such sensitive monitoring opens the door to more dynamic and personalized surveillance. Instead of relying on standardized imaging schedules for all patients, clinicians could intensify monitoring for those who test positive for molecular residual disease (MRD), potentially catching recurrence at its earliest and most treatable stage. This aligns with a broader movement in oncology toward using liquid biopsies to provide a real-time picture of a patient's cancer status.

A New Contender in a Crowded Field

SAGA Diagnostics enters a competitive but rapidly growing liquid biopsy market. Established players like Natera, with its Signatera test, and Guardant Health, with Guardant Reveal, have already made significant inroads in the colorectal cancer MRD space. These tests typically rely on identifying patient-specific single nucleotide variants (SNVs) to track residual disease.

However, SAGA is positioning its Pathlight technology with a key differentiator: its focus on detecting structural variants (SVs). SVs are large-scale rearrangements of a chromosome, which the company argues are highly stable, unique to a patient's tumor, and present from the earliest stages of cancer development. By targeting these large, stable markers, Pathlight is engineered to achieve ultrasensitive detection, what SAGA describes as a “no sensitivity cliff.” This allows the technology to confidently identify even a single ctDNA molecule as a positive signal, avoiding the background noise that can limit the sensitivity of other next-generation sequencing methods.

The CITCCA data provides powerful clinical validation for this technological approach. By demonstrating that over 40% of high-risk patients fall into the ultrasensitive detection range, SAGA makes a compelling case that its technological edge translates directly into identifying more patients who need further attention, strengthening its competitive position.

The Path to Clinical Adoption

While the clinical data is compelling, the journey to widespread adoption in routine care involves navigating significant regulatory and reimbursement hurdles. For SAGA Diagnostics, the path forward is illuminated by its own recent successes.

The Pathlight test is already commercially available in the U.S. for early-stage breast cancer and, critically, has secured Medicare coverage for recurrence monitoring in that indication. This precedent demonstrates the company's ability to generate the necessary evidence to satisfy payers of its clinical utility and cost-effectiveness.

The robust data from the CITCCA study serves as the foundational evidence needed to pursue a similar path for a colorectal cancer indication. The next steps will involve engaging with the U.S. Food and Drug Administration (FDA) for regulatory clearance and presenting this comprehensive data package to both public and private payers. The strong hazard ratio and clear impact on risk stratification provide a powerful argument for reimbursement, as accurately identifying patients for treatment escalation or de-escalation is central to modern value-based healthcare.

As the field of oncology continues its march toward precision medicine, the ability to see what was previously invisible is paramount. With the evidence from the CITCCA study, ultrasensitive MRD testing is poised to become an indispensable tool in the fight against colorectal cancer, offering a clearer view of patient risk and a more personalized map for the treatment journey ahead.