Blood Test Can Help Guide Treatment Decisions for Women 70 and Over with Estrogen Receptor-Positive Breast Cancer

Clinicians have previously had limited tools to guide individualized treatment decisions with this age group and this type of cancer.

Matt MacKenzie

March 23, 2026

2 min read

Key Highlights

Blood-based ctDNA testing can help identify which elderly breast cancer patients are unlikely to benefit from surgery or radiation.
Patients with negative ctDNA post-therapy tend to have stable disease, possibly avoiding invasive treatments.
Persistent positive ctDNA suggests the need for additional interventions to control tumor growth.
Home-based blood monitoring offers a convenient way to track treatment response over time.
Careful patient education and shared decision-making are crucial for personalized treatment planning.

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A study published in Clinical Cancer Research found that a “blood-based test may help guide treatment decisions for a carefully selected group of women age 70 and over who have estrogen receptor-positive breast cancer.”

For some women in this age group with this type of cancer, “determining ‘the right size’ of treatment can be challenging, in part because clinicians have limited tools to guide individualized treatment decisions.” The researchers then analyzed “blood samples for circulating tumor DNA (ctDNA), small fragments of genetic material shed by cancer cells. They assessed whether the presence or absence of these fragments could identify patients who were unlikely to respond to endocrine therapy alone.”

Patients whose ctDNA test was negative were “more likely to have stable disease or tumor shrinkage.” This means surgery and radiation “probably wouldn’t improve outcomes for this group of patients.” Meanwhile, patients whose ctDNA remained positive post-endocrine therapy were “more likely to experience tumor growth while receiving the medication, suggesting that surgery or other treatments may still be necessary to achieve tumor control in this group.”

Based on these findings, the researchers suggest that “having a monitoring option that can be conducted from home may be an important consideration. For both patients and caregivers, the researchers emphasized the importance of careful patient education and shared decision-making throughout the treatment process.”