Breast Cancer Monitoring: Why We Track More Than “How You Feel”

One of the hardest parts of breast cancer survivorship is the uncertainty—especially when someone feels “fine,” but still wants clarity about what’s happening beneath the surface. That is why monitoring matters. In addition to symptom tracking and routine oncology follow-up, circulating tumor DNA (ctDNA) testing is increasingly discussed as a way to detect molecular residual disease (MRD)—a signal that cancer may be present at levels too low for imaging or symptoms. In our clinic, we often support breast cancer patients who are using Signatera, a personalized (“tumor-informed”) ctDNA test, as part of their broader oncology monitoring plan.

ctDNA MRD testing is very promising prognostically: a positive test during follow-up is consistently associated with a higher risk of recurrence, and it can sometimes detect relapse months (and occasionally longer) before clinical/imaging detection.

A key prospective/serial follow-up study (JCO Precision Oncology, 2024) showed that:

• Serially negative ctDNA results were associated with better outcomes.

• ctDNA positivity often preceded overt clinical recurrence, with reported lead time, median reported in the paper and some patients detected earlier than imaging.

There are also broader reviews in 2025 summarizing MRD in breast cancer that describe detection rates and lead times across settings and highlight the overall prognostic value of ctDNA in the survivorship/late-adjuvant period.

The big limitation (why it’s not universal standard of care yet)

What we still do not have at large scale studies is definitive evidence that acting on ctDNA results (treating earlier because ctDNA is positive) reliably improves hard outcomes like overall survival compared with standard monitoring. This “clinical utility” gap is why experts emphasize the need for prospective interventional trials before ctDNA alone guides treatment changes. At Katallage, we let patients know the data.

3) Where Signatera specifically fits

Signatera is a “tumor-informed” ctDNA test used for MRD detection and surveillance in multiple cancers, including breast cancer. It has published/ongoing evidence and is being used in research and clinical contexts.

4) Practical, clinic-use framing

• Guideline-based survivorship remains the foundation (symptoms + exams + mammography).

• ctDNA MRD tests like Signatera can add a risk signal—sometimes earlier than imaging—but larger clinical trials have not been done to show the best action plan for a positive result.

We pair this with continued integrative support—often including IV therapy for resilience and recovery—and we bring an anthroposophic lens to the deeper question of root causes: inflammation, immune regulation, metabolic terrain, stress physiology, and the person’s whole-life context. Monitoring is not meant to create fear; it’s meant to bring earlier insight and wiser decision-making, in collaboration with the oncology or medical team.

Learn how our integrative support and monitoring collaboration can fit your care plan.