Blood test able to detect cancer a year in advance

A team at the Francis Crick Institute, based in London, has discovered a new way of analysing blood in patients who had previously suffered from cancer to determine whether there was a possibility of recurrence. The test, known as a liquid biopsy, is able to detect traces of unstable cancer DNA in the blood, which give clues to cancer development in patients.

The trial involved 100 lung cancer patients, with scientists seeing increasing levels of cancer DNA in the blood of patients who would go on to have their cancer reappear. The process involved patients having their blood examined every six to eight weeks. This allowed the scientists to track the DNA taken from samples in the first instance of the cancer in patients before scanning to see if the same DNA reappeared in tests, indicating recurrence.

"This means that for the first time in lung cancer, we could open up clinical trials where patients with disease, that isn’t yet visible through medical imaging, can be treated with new drugs," says Professor Charles Swanton, who led the study. "We could also use tumour DNA in the blood to monitor how well the treatments are working."

The test, named TRACERx, was able to predict, in 24 patients that had in-depth analysis of their blood, to a 92% accuracy who was likely to relapse. The potential for test means that not only could the test be used to determine whether cancer was likely reoccur but also to treat signs of cancer before it was able to take hold. It could also mean that the efficacy of treatments could be determined as patients are treated, via the blood tests.

In one particular instance, a patient was found to have elevated levels of tumour DNA in the blood with no evidence of the return of cancer. Researchers were initially puzzled but, a year later, cancer was found through a CT scan.

It is understood that the later cancer is caught, the more difficult it is to treat. The potential for cancer to be caught early could then make treatment easier. It would also allow for new drug targets to be developed specifically for early signs of cancer reoccurrence.