A new blood test can predict if breast cancer will come back years before it shows up on scans. The “ultra-sensitive” test can pick up traces of a tumour ’s DNA ahead of a full relapse, when it is much harder to treat. It was found to be 100% accurate at predicting which patients would see their cancer come back, paving the way for treatment to start before it becomes incurable.
The “liquid biopsy” uses whole genome sequencing to look for genetic faults in a patient’s DNA, which can be a sign of cancer. A team of researchers from the Institute of Cancer Research (ICR), London, conducted the trial on 78 patients with different types of early breast cancer. The test looks for 1,800 mutations in the blood which are released by cancer cells, known as circulating tumour DNA (ctDNA).
It successfully found this ctDNA in 11 woman who all went on to see their cancer return. None of the other women relapsed. Blood samples were tested at the point of diagnosis, then again following surgery and chemotherapy.
These tests were then repeated every three months for the next year and every six months for the next five years. On average, the blood test detected cancer 15 months before symptoms appeared or it showed up on scans. The earliest was 41 months before a scan confirmed the diagnosis, according to the results presented at the American Society of Clinical Oncology conference in Chicago.
Detection of the tumour DNA at any point after surgery or during the follow-up period saw.