Advance in cancer tracking reported
Compared with mammograms
MILWAUKEE - A radioactive tracer that can find cancer in dense breasts showed promise in its first big comparison test against mammograms, revealing more tumors and giving fewer false alarms, doctors reported yesterday.
The experimental method - molecular breast imaging, or MBI - would not replace mammograms for women at average risk of the disease.
But it might become an additional tool for higher-risk women with a lot of dense tissue that makes tumors hard to spot on mammograms, and it could be done at less cost than an MRI, or magnetic resonance imaging. About one-fourth of women 40 and older have dense breasts.
"MBI is a promising technology" that is already in advanced testing, said Carrie Hruska, a biomedical engineer at the Mayo Clinic in Rochester, Minn., which has been working on it for six years.
She gave results in a telephone news briefing yesterday and will present them later this week at an American Society of Clinical Oncology conference in Washington.
Mammograms - a type of X-ray - are the chief way now to check for breast cancer. MBI uses radiation, too, but in a different way. Researchers tried both methods on 940 women who had dense breasts and a high risk of cancer because of family history, bad genes, or other reasons.
Thirteen tumors were found in 12 women - eight by MBI alone, one by mammography alone, two by both methods, and two by neither.
The two missed cancers were found on subsequent annual mammograms, physical exams, or other imaging tests.
"These images are quite striking. You can see how the cancers would be hidden on the mammograms," Hruska said.
Mammograms gave false alarms - led doctors to conclude that cancer was present when it was not - in about 9 percent of patients, compared with only 7 percent for MBI.
The MBI tests led to more biopsies than mammograms did, but they more often revealed cancer.
The next test will be to see how MBI stacks up against MRI. The federal government is paying for a new study Mayo is leading that compares the two in 120 high-risk women with dense breasts.
MRI is often used now for women with dense breasts, but it gives many false alarms that lead to unnecessary biopsies. Doctors hope MBI will prove more accurate and cost less - under $500 versus more than $1,000 for an MRI.
"We all know that mammography is, in and of itself, an imperfect tool, and we clearly need to do better in the future," said Dr. Eric Winer of Dana-Farber Cancer Institute in Boston, a spokesman for the oncology group. "It is fair to say that MRI will not solve all problems either."
One drawback of MBI: It uses about 8 to 10 times the radiation of mammograms, a dose that engineers like Hruska are trying to lower with newer technology. Other medical centers also are testing MBI. 