A new blood test can accurately identify different types of breast cancer, allowing patients to be matched to the most effective treatment without the need for a tissue biopsy.
The test, called the Breast Circulating Methylation Assay (BCMA), can also track changes in a cancer’s type over time, enabling rapid adjustments to treatment if the tumor evolves.
Targeted Treatment for Specific Cancer Types
Breast cancer is not a single disease but a group of distinct types, such as oestrogen receptor positive, human epidermal growth factor receptor 2 positive (ER+/HER2+) cancers, which account for about 10% of cases. Each type requires specific therapies. However, roughly 20% of advanced tumors can change type, rendering ongoing treatments less effective.
Researchers at The Institute of Cancer Research (ICR), London, hope the BCMA test will allow patients to receive the right treatment sooner. They also see potential for the technology to be applied to other cancers in the future.
Detecting Tumor DNA in the Blood
Presented at the San Antonio Breast Cancer Symposium, the study analyzed blood samples from patients in five clinical trials, detecting circulating tumor DNA (ctDNA) released by cancer cells into the bloodstream. Using machine learning, scientists at the Breast Cancer Now Toby Robins Research Centre developed the test to identify ctDNA markers specific to the main breast cancer types: ER positive or negative, HER2 positive or negative, and triple-negative breast cancer.
Tracking Cancer Type Changes
In the study, funded by Breast Cancer Now, the Wellcome Trust, and Cancer Research UK, 191 blood samples from 86 patients were analyzed. Researchers compared the blood test results with tissue biopsies taken on average more than five years apart.
The cancer type changed in 19% of cases, and the BCMA test was nearly 90% accurate at detecting these switches. In 8% of samples, tissue biopsies showed a switch—for example, from ER+/HER2- to triple-negative—but the blood test revealed both types were present simultaneously.
This finding suggests patients could benefit from therapies targeting both cancer types, such as aromatase inhibitors for ER+ tumors and Trodelvy (sacituzumab govitecan) for triple-negative cancers. Additionally, 29% of tumors classified as HER2- by tissue biopsy were HER2+ in the blood test, potentially expanding the number of patients eligible for HER2-targeted therapies.
Towards Non-Invasive, Personalized Care
Dr. Nida Pasha, Clinical Research Fellow at ICR and first author of the study, said:
“Our test detects unique patterns in circulating tumor DNA to pinpoint the exact breast cancer type. This can guide treatment decisions. The next step is to assess the test in clinical trials to see if it improves patient outcomes.”
Professor Nicholas Turner, Professor of Molecular Oncology at ICR, added:
“Around 20% of advanced breast cancers change type, which can lead to treatment failure if undetected. Our research shows it is possible to identify breast cancer type from a blood test, allowing changes to be tracked over time and treatment adapted accordingly.”
Professor Kristian Helin, Chief Executive of ICR, said: “This technology represents a step towards smarter, faster, and kinder cancer care. Non-invasive blood tests could soon complement or even replace biopsies, enabling earlier intervention when treatment resistance develops.”
Dr. Simon Vincent, Chief Scientific Officer at Breast Cancer Now, said: “With thousands of women dying from breast cancer annually in the UK, innovative tools like this test could transform how we monitor and treat the disease. These early results are promising, and future clinical trials will determine its role in routine care.”
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