Blood Test Could Refine Breast Cancer Care for Seniors

Researchers find circulating tumor DNA test may help guide treatment decisions for older women with estrogen receptor-positive breast cancer.

Mar. 20, 2026 at 1:09am

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A study published in Clinical Cancer Research found that a blood-based test for circulating tumor DNA (ctDNA) may help guide treatment decisions for women age 70 and over who have estrogen receptor-positive breast cancer and are considering endocrine therapy as the primary treatment. Patients whose ctDNA test was negative were more likely to have stable disease or tumor shrinkage, suggesting surgery and radiation may not be necessary. In contrast, patients whose ctDNA remained positive after endocrine therapy were more likely to experience tumor growth, indicating additional treatments may still be needed.

Why it matters

Determining the right treatment approach for older women with breast cancer can be challenging, as clinicians have limited tools to guide individualized decisions. This study suggests a blood-based ctDNA test could help identify which patients are less likely to respond to hormone therapy alone, potentially avoiding unnecessary side effects from surgery and radiation.

The details

Researchers analyzed blood samples for circulating tumor DNA (ctDNA) to assess whether the presence or absence of these genetic fragments could identify patients unlikely to respond to endocrine therapy. Patients whose ctDNA test was negative, either at the start of treatment or after beginning endocrine therapy, were more likely to have stable disease or tumor shrinkage, suggesting surgery and radiation may not be necessary. In contrast, patients whose ctDNA remained positive after endocrine therapy were more likely to experience tumor growth, indicating additional treatments may still be needed.

  • The study was published on March 20, 2026.

The players

UPMC Hillman Cancer Center

A comprehensive cancer center that is part of the University of Pittsburgh Medical Center (UPMC) network.

University of Pittsburgh School of Medicine

The medical school of the University of Pittsburgh.

Priscilla F. McAuliffe, M.D., Ph.D.

A breast surgical oncologist at UPMC Hillman Cancer Center and associate professor of surgery at the University of Pittsburgh School of Medicine.

Neil Carleton, M.D., Ph.D.

The lead author of the study and a post-doctoral fellow at the University of Pittsburgh.

Natera, Inc.

A company that provides genetic testing and diagnostics services.

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What they’re saying

“We are learning that not every patient needs the same treatment based simply on their diagnosis, and instead, care should be right-sized for each individual.”

— Priscilla F. McAuliffe, M.D., Ph.D., Breast surgical oncologist at UPMC Hillman Cancer Center and associate professor of surgery at the University of Pittsburgh School of Medicine

“Making care more convenient for patients, including access to clinical trials, is a priority at UPMC Hillman Cancer Center.”

— Neil Carleton, M.D., Ph.D., Lead author and post-doctoral fellow at the University of Pittsburgh

What’s next

Larger studies are needed before this approach could be used routinely.

The takeaway

This study suggests a blood-based circulating tumor DNA test could help guide treatment decisions for older women with estrogen receptor-positive breast cancer, potentially avoiding unnecessary side effects from surgery and radiation for those less likely to respond to hormone therapy alone.