BCMA blood test can track cancer changes and match patients to the right treatment
A new blood test can accurately identify different types of breast cancer and identify changes over time, allowing patients to be matched to the correct treatment without the need for a biopsy.
The novel technology, called Breast Circulating Methylation Assay (BCMA), can identify when breast tumors switch to a different type. The findings were recently presented at the San Antonio Breast Cancer Symposium (9-12 December 2025, TX, USA). The authors note that the test could help patients get matched to the correct treatments at an earlier stage.
There are several types of breast cancer that have different receptors and each requires a specific treatment regimen. It has previously been noted that approximately 20% of advanced tumors will switch type, resulting in the initial treatment becoming ineffective.
In this study, a multi-institutional group of researchers analyzed blood samples from breast cancer patients in five clinical trials. Using machine learning technology, the researchers developed a test to identify markers on ctDNA, which are specific to different breast cancer types ER (+ or -), HER2 (+ or -) and TNBC.
In total, the team analyzed 191 blood samples from 86 patients and found that 19% of breast cancer samples switched type.
The BCMA test was accurate in detecting 90% of these switches. The team compared the accuracy of the BCMA test with two tissue biopsies taken on average 5 years apart. It was noted that the BCMA test provided more information than the tissue biopsies. For example, in 8% of the samples, tissue biopsies showed that the patients’ cancer had switched type – for example, from ER+/HER2- to triple negative breast cancer (TNBC) – but the blood test showed that both types of breast cancer were present at the same time.
“Our research is the first to show that it is possible to identify breast cancer’s type from a blood test – meaning that any changes to this type can be tracked easily over time, and treatment can be altered if necessary,” explained Nicholas Turner from The Royal Marsden NHS Foundation Trust.
Additionally, the blood test picked up more samples as HER2 positive than the tissue biopsy, meaning more patients could benefit from being switched to HER2+ specific treatments.
First author of the study, Nida Pasha from The Institute of Cancer Research commented on the wider impact of the study: “The technology behind this test isn’t limited to breast cancer – it could be applied across many cancer types.”
“This innovative blood test – developed by our researchers – has the potential to transform how we monitor and treat breast cancer, ensuring people receive the most effective therapies as early as possible. While we need further research and clinical trials before this test can be used in routine care, these early results are hugely promising,” noted Simon Vincent (Chief Scientific Officer at Breast Cancer Now), which funded the study along with the Wellcome Trust and Cancer Research UK.