A blood test can predict whether breast cancer will come back years before it shows up on scans, allowing treatment to begin before it becomes incurable.
The “ultrasensitive” test can detect traces of a tumor’s DNA before a full relapse, when it is much more difficult to treat.
It was found to be 100 percent accurate in predicting which patients would see their cancer return, up to three and a half years earlier than conventional scans.
Doctors say it could have a “transformative effect” on breast cancer outcomes, saving many of the 11,500 lives lost each year in the UK to the disease.
“Liquid biopsy” uses whole-genome sequencing to look for genetic flaws in a patient’s DNA, which may be a sign of cancer.
A blood test can predict whether breast cancer will return years before it shows up on scans, allowing treatment to begin before it becomes incurable (File Image)
Researchers at the Institute of Cancer Research (ICR) London carried out the trial on 74 women with different types of early breast cancer.
The test looks for 1,800 mutations in the blood released by cancer cells, known as circulating tumor DNA (ctDNA).
They successfully detected this ctDNA in 11 women, and in all of them the cancer returned. None of the other women relapsed.
Blood samples were tested at diagnosis and then again after surgery and chemotherapy. The tests were then repeated every three months for the following year and every six months for five years.
On average, the blood test detected the cancer 15 months before symptoms appeared or it showed up on scans, the current method used by the NHS to monitor cancer survivors.
The earliest was 41 months before a scan confirmed the diagnosis, according to results presented at the American Society of Clinical Oncology conference in Chicago.
All those who showed signs of tumor DNA at some point after surgery were found to have a higher risk of future relapse and worse overall survival.
Lead researcher Dr Isaac García-Murillas of the ICR said the findings “lay the foundation for better post-treatment monitoring and potentially life-prolonging treatment for patients”.
Doctors say it could have a “transformative effect” on breast cancer outcomes, saving many of the 11,500 lives lost each year in the UK to the disease (File Image)
He added: ‘Breast cancer cells may remain in the body after surgery and other treatments, but there may be so few of these cells that they are undetectable in follow-up scans. These cells can cause patients to relapse many years after their initial treatment.
“Ultrasensitive blood tests could offer a better approach for long-term follow-up of patients whose cancer is at high risk of coming back.”
Other blood tests have also been developed that look for DNA evidence of recurring cancer. However, they look for only between 16 and 50 mutations in gene regions that are directly related to the disease.
Developed by the American company Personalis, this new test is approximately 100 times more sensitive.
Dr. García-Murillas added: “It is very important to have a more sensitive test for this group of patients with early-stage breast cancer, as they tend to have a very low amount of cancer DNA in their blood.”
Women who relapsed in the study survived an average of just over five years.
Researchers said further studies were being done to see if patients could start treatment as soon as signs of recurrence were detected, potentially preventing the disease from spreading and becoming incurable.