A simple blood test can detect if breast cancer will return years before it shows up on a scan.
The ultra-sensitive test looks for tiny fragments of tumour DNA in the bloodstream, and researchers report that it was 100% accurate in predicting which patients would relapse after surgery.
Doctors now hope it will have a ‘transformative effect’ on outcomes for breast cancer, with the potential to prevent many deaths each year.
A team from The Institute of Cancer Research, London, used an ultra-sensitive liquid biopsy to detect the presence of tiny amounts of cancer DNA left in the body following treatment for early breast cancer.
The findings, presented at the American Society of Clinical Oncology (ASCO) annual meeting in Chicago this month, involved analysing blood samples from the ChemoNEAR sample collection study for circulating tumour DNA (ctDNA) released into the bloodstream by cancer cells.
The researchers, based at the Breast Cancer Now Toby Robins Research Centre at The Institute of Cancer Research (ICR), were able to identify all patients from the study who later relapsed by detecting molecular residual disease.
By finding those most likely to relapse, the ICR scientists hope the results will pave the way for a new strategy for treating recurrent cases of breast cancer.
The study’s approach involves genome sequencing (WGS). This enabled researchers to identify up to 1,800 mutations, which are much more sensitive and include many cancer-related changes that could occur in a patient’s DNA.
Blood samples from 78 patients with different types of early breast cancer (23 with triple-negative breast cancer, 35 with HER2+ breast cancer, 18 with hormone receptor+ breast cancer and two with an unknown subtype) were screened for ctDNA.
Samples were collected from the women at diagnosis before their therapy, after the second cycle of chemotherapy, following their surgery, and every three months during follow-up for the first year. After that, samples were collected every six months for five years.
The results showed that detection of ctDNA at any point after surgery or during the follow-up period was associated with a high risk of future relapse and poorer overall survival.
Lead study author Isaac Garcia-Murillas is a staff scientist in the Molecular Oncology Group at The Institute of Cancer Research in London.
He said: ‘This proof-of-principle retrospective study lays the groundwork for better post-treatment monitoring and potentially life-extending treatment in patients. This approach goes one step further and uses whole-genome sequencing to… uniquely identify the patient’s cancer recurrence from a blood sample. A more sensitive test is crucial for this group of patients with early breast cancer, as they tend to have a very low amount of cancer DNA in their blood.’
Co-study author Nicholas Turner, Professor of Molecular Oncology at The Institute of Cancer Research and a consultant medical oncologist at The Royal Marsden National Health Service Foundation Trust, said: ‘Testing a patient’s blood for ctDNA will allow clinicians to diagnose the return of cancer at the very earliest stage. However, further research and testing are needed before we can demonstrate whether detecting molecular residual disease could guide therapy in the future.
‘The ongoing TRAK-ER trial at The Royal Marsden, for example, is using a different molecular test to identify circulating tumour DNA and predict relapse in [patients with oestrogen receptor–positive] breast cancer. This trial is looking at whether relapse in patients with residual disease could be prevented by altering their treatment.’
According to the World Health Organisation (WHO):
• Breast cancer caused 670,000 deaths globally in 2022.
• Roughly half of all breast cancers occur in women with no specific risk factors other than sex and age.
• Breast cancer was the most common cancer in women in 157 countries out of 185 in 2022.
• Breast cancer occurs in every country in the world.
• Approximately 0.5-1% of breast cancers occur in men.
Photo caption - Blood test is early warning sign of breast cancer relapse
