A new blood test can predict the return of breast cancer years before patients relapse, according to a new study.
The ultra-sensitive test looks for signs that cancerous cells remain after treatment. It can detect tiny amounts of cells that may be too small for follow-up scans to pick up.
Early detection means patients can be treated “without waiting for incurable, advanced disease to develop and show up on a scan”, according to the study’s authors from London’s Institute of Cancer Research (ICR).
“Breast cancer is much easier to treat before it spreads to other parts of the body, so it is vital to be able to detect signs of recurrence of the disease as early as possible to give people the best chance of survival,” said Professor Kristian Helin, chief executive of the ICR.
Blood tests for cancer already exist but researchers say this one can detect a wider range of cancerous cells earlier than current blood tests.
This is because it scans for the whole cancer genome instead of only focusing on the parts of cancer cells that directly relate to diseases.
“A more sensitive test is very important for this group of early breast cancer patients as they tend to have a very low amount of cancer DNA in their blood,” said report author Dr Isaac Garcia-Murillas from the IRC.
Seventy-eight women with different types of breast cancer took part in the study and 11 relapsed after their initial treatment.
The new blood test detected cancerous cells before all 11 women relapsed, with the potential relapses being spotted around three months earlier than current tests on average.
In one patient, the test spotted cancer cells 41 months before she relapsed.
Blood samples were collected from the women when they were diagnosed, after their second cycle of chemotherapy, after their surgery and every three months during follow-up for the first year.
After that, samples were collected every six months for the next five years.
Nearly 56,000 people are diagnosed with breast cancer a year, according to Cancer Research UK.
This study now “lays the groundwork for better post-treatment monitoring and potentially life-extending treatment in patients”, according to Dr Garcia-Murillas.
