Women's Health: MRI scan pinpoints hidden breast tumours

Women with a recent diagnosis of cancer in one breast should have the other scanned for tumours as well, according to a large North American study.

In particular, the scan should be done with magnetic resonance imaging (MRI), because it may detect tumours missed by standard examinations, such as an X-ray-based mammography.

The research, which was conducted at 25 sites in the U.S. and Canada, showed MRI detected cancer in the opposite breast in more than three per cent of 969 women who had been diagnosed with cancer in one breast within the previous two months. In all cases, the women had no apparent abnormalities on standard examinations of the opposite breast. MRI uses powerful magnets and radio waves to create images of tissue inside the body.

"This study really supports the use of MRI at the time of a woman's breast cancer diagnosis," says Dr. Constance Lehman, co-principal investigator of the trial and a professor of radiology at the University of Washington Medical Center in Seattle. "For women who have a breast cancer diagnosis, they should talk to their specialist about the potential benefits of having an MRI added to their diagnostic workup before that treatment is initiated."

A total of 121 women had a breast biopsy as a result of the MRI findings. In 91 cases, the tumour turned out to be benign. But 30 specimens were positive for cancer.

"Some women are told that if their breast tissue is not dense, the MRI will not be helpful. We did not find that to be the case," Lehman says. "The MRI was as helpful in women with fatty breast tissue as it was in women with dense breast tissue."