In a new study, researchers from Brigham and Women’s Hospital found a set of easily measurable risk factors that can determine the survival benefit offered by radiation therapy for patients with ductal carcinoma in situ (DCIS). DCIS is the most common type of breast cancer in women, according to the Centers for Disease Control and Prevention (CDC).
Women with DCIS have cancer in the lining of the milk ducts that has not spread to other tissues in the breast. Although an estimated 60,000 women will be diagnosed with DCIS in 2016, the 10-year survival rate for the disease is 98 percent, according to the CDC.
"DCIS has a very low breast cancer mortality, which means that as an oncology community, we must be cognizant of overtreatment," said study co-author Mehra Golshan, MD, in a press release. Dr. Golshan is a surgical oncologist at Brigham and Women's.
Radiation therapy has become a widely accepted treatment after surgery for patients with DCIS. Researchers said this study could provide guidelines by which doctors can estimate the survival benefit from radiation based on a patient's individual case.
This study looked at more than 32,000 DCIS patients — more than 20,000 of whom underwent radiation therapy after surgery and more than 11,000 of whom underwent surgery alone.
Breast cancer death rates were low for both groups, at 1.8 percent for the radiation group and 2.1 percent for the surgical group.
Each patient was assigned a prognostic score between 0 to 6 based on three risk factors: the patient’s age, tumor size and nuclear grade (how cancer cells look under a microscope).
For patients with a higher prognostic score, radiation proved to have a significant survival benefit. Patients who scored either 4 or 5 on the test and underwent radiation after surgery saw a nearly 70 percent reduction in breast cancer death. Patients who scored lower on the test saw no significant difference.
"Using three factors that are routinely measured, we can predict whether there will be a survival benefit or no survival benefit for patients receiving radiation therapy," said lead study author Yasuaki Sagara, MD, in a press release."Our finding suggests, for the first time, that patients with more aggressive cancer who are at higher risk may actually live longer if they are treated with radiation therapy."
Dr. Sagara is also a surgical oncologist at Brigham and Women's.
Drs. Golshan and Sagara noted that, although this study found that radiation provided only a slight survival benefit to low-risk DCIS patients, other studies have found the opposite. They recommended thorough counseling about the risks and benefits of radiation therapy before any DCIS patient makes a decision.
This study was published online Feb. 1 in the Journal of Clinical Oncology.
The National Institutes of Health funded this research. Study author Rachel A. Freedman disclosed funding from Genentech, Puma and Eisai. Dr. Golshan was a consultant at Abbvie.