Breast cancer relapse could be predicted with new blood test

by Jonathan Vernon

Atest that identifies genetic information in the blood picks up sensitive amounts of DNA that can be used to shape decisions about cancer treatment.

One of the challenges of modern medicine is to know if and when a cancer patient will relapse. A new study shows that months before tumors are visible on hospital scans, a “mutation-tracking” blood test can pick up valuable signs of a cancer’s return.

The study, undertaken by researchers at The Institute of Cancer Research (ICR) and The Royal Marsden NHS Foundation Trust – both in the UK – is an important step toward changing the way cancer is monitored in the clinic and informing treatment decisions.

The clue to identifying a return of cancer cells is to look at circulating tumor DNA present in the blood. These are cancer cells left behind that may seed new tumors even after treatment.

By monitoring patients with blood tests taken after surgery, the study says, and then every 6 months in follow-up, the researchers were able to predict very accurately who would experience a relapse.

The study involved 55 women who had been successfully treated for early-stage breast cancer.

It was found those who tested positive for circulating tumor DNA were at 12 times greater risk of relapse compared with those who tested negative. In addition, the blood test was able to detect cancer recurrence an average of 7.9 months before any visible signs appeared.

Explaining what the researchers are attempting to achieve with the blood test, Kat Arney, science information manager at Cancer Research UK, told BBC Radio:

“They are looking for ways to detect DNA that has been shed by tumor cells into the bloodstream and saying can we use this DNA as a way of monitoring if the cancer is coming back – how it is changing, how it is evolving in the body – and then could we use that to monitor cancer and pick up potentially when it has come back without having to give scans or biopsies.”

“There are still challenges in implementing this technology […] but the information that it provides could make a real difference to breast cancer patients, ” added Dr. Nicholas Turner, team leader in molecular oncology at ICR and consultant medical oncologist at The Royal Marsden.

FINDINGS COULD BE APPLIED TO ALL BREAST CANCER SUBTYPES

Because the researchers were searching for mutations common to various breast cancer types, they found the test could be applied to all subtypes of the disease.

“This test could help us stay a step ahead of cancer by monitoring the way it is changing and picking treatments that exploit the weakness of the particular tumor, ” says Prof. Paul Workman, chief executive at ICR.

The potential of this new test, Arney told BBC Radio, is to “separate those mutations that are driving the cancer from all the other genetic chaos that is going on in there, looking at how we can target these particular gene faults in this particular person, and those are the same faulty genes that are driving their relapse when the cancer comes back.”