Tests to detect recurrence in breast cancer patients may soon be underway, thanks to the recent discovery of genetic variants that usually occur only in relapsing cancer cases.

The new research, done by a team from the Wellcome Trust Sanger Institute in Cambridge and to be presented at the 2015 European Cancer Congress in Vienna, Austria, found that genetic factors that drive returning breast cancer are distinct from those in non-returning tumors.

The genes responsible for recurrence can then be targeted for early treatment.

The team headed by clinical research oncologist Dr. Lucy Yates analyzed DNA from tumor samples from 1,000 breast cancer patients, including 161 individuals whose cancer had recurred or spread (metastasized).

They compared primary and secondary tumors and found genetic differences in the secondary cancers that were quite unusual in cancers diagnosed for the first time. This knowledge is believed to assist in the selection of the best treatment to target a specific genetic mutation.

"[W]e hope that in the future it will be possible at the point of diagnosis to look at the cancer genes in an individual's cancer and determine whether it is likely to return in the future and, if so, to select a personalized therapy to prevent that event," Dr. Yates said.

European Cancer Organisation scientific co-chair Prof. Peter Naredi said the information to be presented by Dr. Yates at the Congress is "very important in the era of precision medicine" and will help doctors choose the right therapy for each breast cancer patient.

Naredi underscores the need to consider a recurring cancer as a new event and pick the right treatment independent of the details of the first occurrence of the disease.

"These are exciting findings and could help doctors offer more personalized treatment to women whose breast cancer has spread or come back—potentially improving their chances of survival,” said Dr. Aine McCarthy, science information officer of Cancer Research UK.

About one in five breast cancers recur after treatment, and they appear either at the same site as the original tumor or spread to other parts of the body.

In 2012, the most recent year numbers are available, 224,147 women in the United States were diagnosed with breast cancer, and 41,150 women died from the leading killer.

Photo: Stephanie Young Merzel | Flickr