A new experimental blood test may be able to detect the warning signs of a relapse into early stage breast cancer in women that have been in remission. According to a report from WebMD, the test may be able to detect cancerous cells months before they show up on CT or MRI scans.

Cancer is typically treated with surgery or radiation therapy, but these treatments can often miss some cancer cells. The new blood test, developed by researchers at the Breakthrough Breast Cancer Research Centre at the Institute of Cancer Research in London, can detect DNA left behind by tumors in the blood stream before they invade other tissues and grow.

The test is still in the preliminary stages, and will not be available for widespread use for a few more years. Once it is readily available, however, it may help detect secondary cases in women who have already undergone treatment.

According to Dr. Nicholas Turner, the study’s lead author, the test will help identify who is at the highest risk of relapse. Women who still have detectable tumor DNA face a much higher risk of redeveloping cancerous tissues after they have been treated.

The study was published in the August 26 edition of Science Translational Medicine, and examined 55 early stage breast cancer patients who had been treated with both chemotherapy and surgery. They gathered blood samples regularly for two years to try and find tumor-specific mutations.

Of the fifteen patients who saw their cancer return, 12 turned up positive results from the blood test an average of eight months before conventional screens showed signs of cancer. While the blood test still has a long way to go, it shows great promise for saving lives.