Getting magnetic resonance imaging (MRI) scans twice a year instead of one annual mammogram is far more effective at detecting early breast cancers in young women with a high-risk genetic profile than mammograms alone.

The results, first presented Dec. 8, 2017, at the annual San Antonio Breast Cancer Symposium and now available online in Clinical Cancer Research, suggest that for women with high-risk genetic mutations, intensive efforts to find small early cancers can be crucial to improving outcomes.

"This study demonstrates for the first time that aggressive breast cancers can be caught early, without excessive recalls or biopsies," said Olufunmilayo Olopade, MD, the Walter L. Palmer Distinguished Service Professor and Associate Dean for Global Health at the University of Chicago Medical Center.

Because of intensive surveillance and high-quality care, the majority of high-risk women in this study did not develop breast cancer, despite the fact that most of these women had genetic mutations such as BRCA1.

Bi-annual dynamic contrast-enhanced magnetic resonance imaging

For their study, "Intensive surveillance with bi-annual dynamic contrast-enhanced magnetic resonance imaging downstages breast cancer in BRCA1 mutation carriers," the researchers enrolled 295 women in a clinical trial. The mean age at entry was 43.3 years.

To join the trial, volunteers had to have a lifetime risk for breast-cancer greater than 20%. More than half (53%) of the women who enrolled had one of 11 known breast-cancer related genetic abnormalities. Seventy-five of those 157 women had BRCA1 mutations, and 61 had BRCA2 mutations.

The study also included women who had been diagnosed with breast cancer or ductal carcinoma in situ before age 35 or had a mother or sister diagnosed with breast cancer before age 50 (before 40 for those of African ancestry). All study subjects had a panel of genetic tests looking for genes associated with a predisposition to breast cancer.

After evaluation by a physician and a genetic counselor, participants were scheduled to undergo a clinical breast examination and a dynamic contrast-enhanced magnetic resonance imaging scan (DCE-MRI) every six months, plus a digital mammogram every 12 months. Those with high-risk mutations who completed five years of the study protocol were offered continued screening.

Over the course of the study, the researchers performed 2,111 DCE-MRIs (on average, about seven for each participant) and 1,223 mammograms (four per participant). They found 17 cancers: four ductal carcinoma in situ and 13 early stage breast cancers.

Fifteen of those cancers occurred in participants with pathogenic mutations. Eleven involved BRCA1, three involved BRCA2, and one involved CDH1. None of the cancers had spread to the lymph nodes. The mean tumor size was 0.61 centimeter (about 1/4 of an inch). All cancers detected during the study were smaller than a centimeter.