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

Share on Pinterest Researchers reveal how a blood test predicted women’s risk of breast cancer recurrence almost 8 months before visible signs appeared.

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.

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.