Personalised DNA blood test ‘could be a game-changer’ in tracking early stage breast cancer progress

Test analyses tiny fragments of tumour DNA in bloodstream

Woman speaking to doctor (iStock)

A new blood test could be up to 100 times more effective at monitoring the progress of early-stage breast cancer than existing tests.

Researchers from the Translational Genomics Research Institute (TGen) in Arizona, US analysed 80 blood samples from 33 women with early-stage and locally-advanced breast cancer.

They used the targeted digital sequencing (TARDIS) test to analyses tiny fragments of tumour DNA in the bloodstream.

The test involves taking a biopsy of the cancer before sequencing its DNA and analysing it for mutations common across all cancer cells.

The scientists, whose research was published in the Science Translational Medicine journal, found that the concentration of tumour DNA in the bloodstream of patients who had no breast cancer cells remaining at the point of surgery was lower than in those that did.

Dr Muhammed Murtaza from TGen explained the test can detect “extremely low concentrations” of cancer DNA at an earlier stage than existing blood tests and is more accurate than others because it looks for DNA sequences specific to each patient’s cancer

The researchers hope the test could be used to monitor the progression of other cancers that are treated with drugs before surgery and track the effectiveness of early treatments.

They also claim it could prevent women from having unnecessary surgery to remove tumour residue after chemotherapy, with lower concentrations in the blood suggesting that treatment has already been successful.

People with early-stage breast cancer can be treated with chemotherapy to shrink their tumour before having surgery to remove any remaining cancer.

However, the experts say that no cancer cells are found in almost a third (30 per cent) of those who go under the knife after treatment.

The scientists will now carry out a study on more than 200 patients to further analyse what the test can show.

Professor Carlos Caldas, director of the Breast Cancer Programme at the Cancer Research UK Cambridge Centre, which contributed to the study, said: “This could be a game changer.

“Instead of patients undergoing six to eight cycles of chemotherapy (15-21 weeks of treatment), after one or two cycles (three to six weeks) we would use the TARDIS test to look for a significant drop in circulating tumour DNA.

Dr Caldas explained that if a drop was not detected, the treatment could be stopped or changed.

"Finding cancer DNA in the blood is like looking for a needle in a haystack,” he added.

“But by developing a test that’s unique to each patient, and looking for mutations present across the entire tumour, we’ve made it much harder for the circulating tumour DNA to hide, significantly increasing the chance of identifying cancer relapses earlier.”

Professor Karen Vousden, Cancer Research UK’s chief scientist, said that although the test is in its early stages “this innovative new technology has the potential to increase the number of people who can benefit.

“A blood test that indicates whether a therapy has been effective could prevent some patients from undergoing further unnecessary treatments, transforming patient care.”

Cancer Research estimated that there were approximately 55,213 new cases of invasive breast cancer from 2014-2016.

Find out how to check your breasts for cancer symptoms here.