A new study highlights the potential of personalized blood tests to monitor treatment response and disease progression in metastatic invasive lobular breast cancer (mILC). Unlike other forms of breast cancer, ILC often spreads in ways that make it hard to detect and monitor with standard scans, leading to late diagnoses and underrepresentation in clinical trials.
In a recent retrospective analysis, personalized blood testing—called circulating tumor DNA (ctDNA) testing—helped track how well treatment was working and spot disease progression in real time. The retrospective analysis involved 66 mILC patients (median age 62.6) and 355 blood samples, using Signatera—a tumor-informed ctDNA test that tracks 16 patient-specific mutations via PCR and next-gen sequencing.
Key Findings:
- When ctDNA levels went down or stayed stable during treatment, 92% of patients showed a positive response on scans.
- If ctDNA levels rose, only 31% of patients had a good response, suggesting rising ctDNA is a warning sign of progression.
- Patients with a positive ctDNA test at any point had a higher risk of death, while those with negative ctDNA results had a 97% survival rate at 6 months and about 90% at 12 months.
- In a few cases, patients whose ctDNA became undetectable after treatment stayed well for extended periods, with no deaths among those who remained ctDNA-negative over a median follow-up of 41 months.
Why This Matters:
ILC often doesn’t show up clearly on scans, making it hard to know if treatments are working. These findings suggest ctDNA testing could address critical gaps in mILC management by:
- Providing real-time feedback on therapy effectiveness
- Identifying early signs of progression before imaging changes
- Reducing reliance on frequent scans for monitoring.
Personalized ctDNA blood tests could become a powerful tool for people with metastatic ILC, helping guide treatment decisions and giving patients and doctors earlier warnings about changes in the cancer—potentially leading to better outcomes, peace of mind, and increased lead time to identify the next treatment and search for clinical trials.
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Reference
Foldi J, Oesterreich S, Tin A, et al. Personalized Circulating Tumor DNA Testing for Detection of Progression and Treatment Response Monitoring in Patients With Metastatic Invasive Lobular Carcinoma of the Breast. JCO Precis Oncol. 2025 May;9:e2400577.
