New blood test can predict breast cancer return years in advance

Dr Isaac Garcia-Murillas. Credit: Institute of Cancer Research.

Scientists have created a new, highly sensitive blood test that can predict the return of breast cancer months or even years before it happens.

This groundbreaking test could greatly improve how we treat and monitor patients at high risk of breast cancer coming back.

A team from The Institute of Cancer Research (ICR) in London developed this test, which was presented at the American Society of Clinical Oncology’s annual meeting in Chicago.

They used a special type of liquid biopsy to find tiny amounts of cancer DNA in the blood of patients who had been treated for early-stage breast cancer.

This test aims to find what is called molecular residual disease – small amounts of cancer DNA left in the body after treatment.

The study involved analyzing blood samples from the ChemoNEAR study for circulating tumor DNA (ctDNA), which is released into the bloodstream by cancer cells.

The researchers at the Breast Cancer Now Toby Robins Research Center at ICR were able to detect very low levels of cancer in the blood, which helped identify all patients from the study who later experienced a relapse.

By identifying patients most likely to relapse, the scientists hope this new test will lead to earlier treatment for recurring breast cancer, potentially before the disease becomes incurable and shows up on scans.

Previous studies have shown that ctDNA blood tests can detect relapses long before they appear on scans. However, these tests often use a technique called whole exome sequencing (WES), which focuses on the protein-coding parts of genes.

In contrast, this study used whole genome sequencing (WGS), which looks at the entire genome.

This approach is much more sensitive, identifying up to 1,800 mutations, thus including a larger number of cancer-related changes that could occur in a patient’s DNA.

The research included blood samples from 78 patients with various types of early breast cancer, including triple-negative, HER2+, hormone receptor-positive, and unknown subtypes.

The samples were collected at diagnosis, after chemotherapy cycles, following surgery, and every three months during the first year of follow-up. After that, samples were taken every six months for five years.

The results showed that detecting ctDNA at any point after surgery or during follow-up was linked to a high risk of future relapse and poorer overall survival.

Molecular residual disease was found in all 11 patients who relapsed, with the median time to clinical relapse being 15 months.

This is an improvement of over three months compared to current tests. The longest time to relapse was 41 months. None of the 60 women without detectable ctDNA relapsed during the follow-up period.

Dr. Isaac Garcia-Murillas from ICR said that while breast cancer cells can remain in the body after treatment, they can be so few that they are undetectable on scans. Ultra-sensitive blood tests could offer a better way to monitor these patients long-term.

Professor Nicholas Turner of ICR emphasized that testing blood for ctDNA allows for the earliest possible diagnosis of cancer’s return. Further research is needed to see if detecting molecular residual disease can guide future therapy.

Professor Kristian Helin, Chief Executive of ICR, said early detection is crucial for easier treatment of breast cancer. Advances in technology that detect cancer cells and DNA with greater sensitivity can transform cancer diagnosis and help develop new strategies for targeted screening and detection.

Dr. Simon Vincent from Breast Cancer Now highlighted the excitement of these findings, noting that early detection could make treatment much more effective. Dr. Richard Chen from Personalis added that the study shows the promise of using an ultra-sensitive test like NeXT Personal to detect the earliest traces of breast cancer recurrence, which could better guide patient management.

These findings are promising steps towards better monitoring and treatment of breast cancer, giving patients a better chance of long-term survival.

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