Ultrasensitive MRD Blood Test Detects Early Breast Cancer Recurrence

SAGA Diagnostics (Morrisville, NC, USA), a company specializing in tumor-informed, blood-based cancer detection and precision medicine, announced the publication of a new study evaluating its Pathlight MRD test in EMBO Molecular Medicine on May 26, 2026. Titled “NeoCircle: Pre- and Post-Operative Circulating Tumor DNA Dynamics Predicts Survival in Neoadjuvant-Treated Early Breast Cancer,” the study highlights the role of ultrasensitive molecular residual disease (MRD) detection in early breast cancer management.

Conducted by researchers at Lund University (Lund, Sweden), the NeoCircle study monitored 136 early breast cancer patients eligible for neoadjuvant therapy (NAT) within the SCAN‑B study across all subtypes. Complete or partial clearance of circulating tumor DNA (ctDNA) during NAT was associated with 10.4% recurrence versus 56.3% among non‑responders. Lack of clearance after therapy predicted poorer breast cancer‑free interval and overall survival compared with pathologic complete response. 

During post-surgical adjuvant monitoring, ctDNA detection preceded relapse up to four years earlier, with a median lead time of 13.8 months. Overall sensitivity for distant recurrence was 86.7%, rising to 92.9% for pathologically confirmed cases and reaching 81.0% when local and CNS-only relapses were included. The findings validate structural variants (SVs) as clinically relevant MRD biomarkers in early breast cancer, showing that ctDNA monitoring across neoadjuvant and adjuvant treatment can predict disease progression months to years in advance and offer insight into clinical outcomes, including survival.

SAGA Diagnostics’ Pathlight MRD is a personalized, tumor-informed, multi-cancer MRD platform designed for ultrasensitive detection of ctDNA. Using a proprietary combination of whole-genome sequencing and digital PCR, Pathlight tracks SVs, stable genomic biomarkers that can support earlier and more precise detection of cancer recurrence and treatment response monitoring.

“With unmatched sensitivity, detecting structural variants at levels as low as 1 part in 10 million, Pathlight provides the resolution needed to identify true molecular residual disease at its earliest stages,” said Lao Saal, MD, PhD, Head, Division of Translational Oncogenomics, and Co-Director, CIRCE Women’s Cancer Research Center, Lund University. “The NeoCircle study, with up to 9.7 years of clinical follow-up, offers a comprehensive view of the durability of SVs and the potential for clinical impact incorporating this approach in the care plan for patients with cancer.”

"SVs represent a foundational biomarker for detecting molecular recurrence before it becomes clinically apparent. The early origin of SVs in tumorigenesis, stability under treatment pressure, and resistance to confounding signals enable ultra-sensitive, tumor-informed detection," said Wendy Levin, MD MS, Chief Clinical Officer of SAGA Diagnostics.

"With 85% of patients in this analysis having Stage I-II disease, where curative intent remains high, we see a clear path toward integrating these biomarkers into clinical practice. This can help guide treatment decisions in real-time, with the potential to improve patient outcomes, including long-term survival," said Dr. Levin.

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