A simple blood test could spare elderly breast cancer patients from unnecessary surgery

UPMC Hillman Cancer Center / University of Pittsburgh School of Medicine / Clinical Cancer Research

Can a blood draw replace a biopsy — or even a scalpel? For a specific group of breast cancer patients, the answer might be getting closer.

Women over 70 with estrogen receptor-positive breast cancer face a particular dilemma. Surgery and radiation carry real costs at that age: scarring, chronic swelling, infection, nerve damage. Hormone-blocking therapy alone works for some patients, but clinicians have had few tools to predict which ones. The result is a treatment-sizing problem — too much intervention for some, too little for others, and limited evidence to tell the difference early.

A study published in Clinical Cancer Research from UPMC Hillman Cancer Center and the University of Pittsburgh School of Medicine now suggests that tracking tiny fragments of tumor DNA in the bloodstream — known as circulating tumor DNA, or ctDNA — may provide exactly that early signal.

What the blood reveals

The researchers collected blood samples from women aged 70 and older who had estrogen receptor-positive breast cancer and were considering endocrine (hormone-blocking) therapy as their primary treatment, without surgery or radiation. They tested these samples for ctDNA — small fragments of genetic material shed by cancer cells into the bloodstream.

The results fell into two clear groups. Patients whose ctDNA test came back negative — either at the start of treatment or after beginning endocrine therapy — were more likely to see stable disease or tumor shrinkage. For this group, surgery and radiation probably would not have improved outcomes.

Patients whose ctDNA remained positive after starting hormone therapy told a different story. They were more likely to experience tumor growth while on medication, suggesting that additional treatment — surgery or alternatives — was still necessary for tumor control.

An important distinction: the study did not evaluate how effective the treatments themselves were. It focused on identifying an early decision window — a moment when doctors could look at a blood result and make a more informed call about what comes next.

Testing from the kitchen table

One of the study's quieter contributions was logistical. Because ctDNA requires only a blood draw, many samples were collected from patients' homes rather than requiring hospital visits. This allowed the research team to enroll patients from across UPMC Hillman's regional network — not just the main academic center in Shadyside, but also sites at UPMC Passavant Cranberry, UPMC Jameson, and UPMC St. Margaret.

"Making care more convenient for patients, including access to clinical trials, is a priority," said lead author Neil Carleton, a post-doctoral fellow at the University of Pittsburgh.

The convenience factor extended to caregivers as well. When surveyed, caregivers reported that supporting a loved one through breast cancer treatment often meant sacrificing work and other responsibilities. A monitoring option that works from home — rather than requiring repeated hospital trips — addresses a burden that clinical trials rarely measure.

What patients and caregivers said

The study included something unusual for a cancer biomarker trial: direct feedback from patients and their caregivers. More than 80% of patients reported that ctDNA test results could help them feel more informed about their treatment decisions, particularly during the first six to twelve months of care.

This matters because treatment decisions for older patients are not purely clinical. Quality of life, recovery time, caregiver burden, and patient preference all factor in. A blood test that provides early clarity about whether hormone therapy is working could reshape those conversations.

"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," said senior author Priscilla F. McAuliffe, a breast surgical oncologist at UPMC Hillman and associate professor of surgery at the University of Pittsburgh.

Small numbers, big caveats

The study enrolled fewer than 50 patients. That is small enough that the findings should be treated as a proof of concept rather than clinical guidance. The researchers are clear: these results are not yet applicable to standard practice. Larger studies will need to validate whether ctDNA tracking reliably predicts treatment response in this population before it could enter routine use.

There are also open questions the study did not address. How often should ctDNA be tested? What threshold of positivity should trigger a change in treatment plan? And does early ctDNA clearance predict long-term outcomes, or just short-term tumor control?

Still, the underlying logic is compelling. If a simple blood test can identify which elderly patients are responding to hormone therapy alone, it could spare a meaningful number of women from procedures they don't need — while flagging those who do need more aggressive treatment before the window closes.

The work was funded by the Hillman Cancer Center Developmental Pilot Program, the Shear Family Foundation, and the National Institutes of Health.