Health

Staff and Wire Reports

MILWAUKEE -- Biomedical engineers at the Mayo Clinic said Wednesday that an experimental method in detecting breast cancer shows promise. This comes after six years of studying molecular breast imaging.

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.

Hruska gave results in a telephone news briefing Wednesday and will present them later this week at an American Society of Clinical Oncology conference in Washington, D.C.

MBI uses a radioactive tracer that captures cancer hiding inside dense breasts, revealing more tumors and giving fewer false alarms, doctors reported Wednesday. Dr. Michael Klouda, a radiologist at East Texas Medical Center, said cancer cells have a higher rate of metabolic activity and that is why the new imaging procedure captures that.

He said that, although the procedure seems promising, there is still a lot to learn about it and it would probably not replace mammograms.

"They have been trying to replace mammograms for about 30 years, but nothing has been as cheap or as fast as the mammogram," he said.

Dr. Klouda noted that MBI takes about an hour to complete for one patient, while technicians can perform about six to seven mammograms in an hour.

Nonetheless, the method has potential to provide another defense against breast cancer, he said.

"It has a role in it. It is evolving but we don't have enough evidence yet. It's only been on the market for about 2-3 years."

Dr. Klouda said ETMC is considering purchasing equipment to use the method within the next year.

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.

Women are given an intravenous dose of a short-acting tracer that is absorbed more by abnormal cells than healthy ones. Special cameras collect the "glow" these cells give off, and doctors look at the picture to spot tumors.

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. Looked at another way, MBI found 10 out of 13 tumors, missing three; mammograms detected three out of 13 tumors and missed 10. Using both methods, 11 out of 13 tumors would have been detected.

"These images are quite striking. You can see how the cancers would be hidden on the mammograms," Hruska said.

Mammograms gave false alarms -- or led doctors to conclude that cancer was present when it was not -- in about 9 percent of patients, compared to only 7 percent for MBI. The MBI tests led to more biopsies than mammograms did, but they more often revealed cancer.

The Susan G. Komen for the Cure foundation and Bristol-Myers Squibb, which makes the imaging agent used in the study, paid for the work.

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 -- less than $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 the Dana-Farber Cancer Center 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 eight to 10 times the radiation of mammograms, a dose engineers like Hruska are trying to lower with newer technology.

Other medical centers also are testing MBI.

"We're just beginning to see what this technology can do," she said.