Predictive blood test hailed as 'incredibly exciting' breast cancer breakthrough |

A new blood test can predict the risk of breast cancer recurrence three years before tumours show up on scans, in a “very exciting” breakthrough that could help more women overcome the disease.

More than two million women are diagnosed with breast cancer each year. It is the most common type of cancer. Although treatments have improved over the past few decades, the cancer often recurs, usually at a more advanced stage.

But personalized liquid biopsies could provide very early warning signs of cancer recurrence, according to research presented at the world's largest cancer conference. Results from a trial of the test, presented at the American Society of Clinical Oncology annual meeting in Chicago, could help reveal which women need preventive treatment and which patients can avoid it.

The test detects tiny traces of cancer DNA in the bloodstream, and trials have shown that it is highly sensitive and can accurately predict the risk of cancer recurrence months or even years before the usual signs and symptoms begin to appear.

Researchers at the Breast Cancer Now Toby Robins Research Centre in London were able to identify all of the patients in the trial who subsequently experienced a recurrence, with the average time to recurrence being 15 months, and the longest being 41 months.

“Early detection is one of our greatest weapons against breast cancer and it's exciting that these early results suggest the test may be able to detect signs of breast cancer recurrence more than a year before symptoms appear,” said Simon Vincent, director of research at Breast Cancer Now, which helped fund the trial.

“This research is still in its early stages, but if we can detect recurrence of breast cancer early, we have a much better chance of being able to treat it and destroy the cancer and stop it from spreading to other parts of the body, at which point it becomes incurable.”

Experts hope that this discovery could lead to strategies that could start treatment earlier. Ultrasensitive liquid biopsy works by finding circulating tumor DNA (ctDNA), which is shed into the bloodstream by cancer cells.

“Breast cancer cells can remain in the body after surgery or other treatments, but these cells may be so low that they go undetected on follow-up scans,” said lead study author Isaac Garcia-Mourillas from the Institute of Cancer Research, London. “These cells can cause a recurrence in breast cancer patients many years after their initial treatment.”

Previous studies have suggested that ctDNA blood tests can identify recurrence before it's seen on a scan. But these tests tend to use a technique called whole-exome sequencing, which typically looks for 16 to 50 mutations. The newer test uses whole-genome sequencing, looking for 1,800 mutations, making it much more sensitive.

The researchers analyzed the blood of 78 women with various types of breast cancer. The new test correctly identified an increased risk of recurrence in all 11 patients who experienced a recurrence during the five-year study period. None of the 60 women in whom the test did not detect ctDNA experienced a recurrence, so there were no false negatives.

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Three further patients had detectable ctDNA at one time but it was lost on subsequent testing. The ICR did not provide complete data for the remaining four patients.

Professor Christian Helin, chief executive of the ICR, said: “Breast cancer is much easier to treat before it spreads to other parts of the body, so it's vital we detect signs of recurrence as early as possible to give patients the best chance of survival.”

“It is exciting to see advances in technologies that allow for more sensitive detection of cancer cells and DNA, uncovering residual disease and detecting early signs of breast cancer recurrence while it may be curative. These approaches are transforming cancer diagnostics.”