New way to spot breast cancer shows promise

Updated Thu. Sep. 4 2008 7:34 PM ET

CTV.ca News

A radioactive tracer that "lights up" cancer cells could prove better at detecting breast cancer in women with dense breast tissue.

A radioactive tracer that "lights up" cancer cells hiding inside dense breast tissue. This technique reveals more tumours and gives fewer false alarms.

"With imaging techniques like this one, and others still in development, we have the opportunity to reduce deaths from breast cancer," Dr. Martin Yaffe of the Sunnybrook Health Sciences in Toronto told CTV's Avis Favaro.

Nearly one-quarter of all women over the age of 40 have breasts filled with dense tissue.

Molecular breast imaging (MBI) is a relatively new screening method. Patients are injected with a radioactive agent that is absorbed by breast tissue.

"The cancer cells absorb much more of this tracer than do normal cells and that leads to this intense lighting up of the tumor on our images," Dr. Deborah Rhodes of the Mayo Clinic in Rochester, Minn., told CTV's Avis Favaro.

The clinic has been working on the technology for six years.

MBI detects three times as many breast tumours as mammography in high-risk women. Although it would not replace mammograms, it might become an additional tool for screening, especially in higher risk women with a dense tissue that makes tumours hard to spot.

"It's really the introduction of a whole new group of agents that will be specifically targeted to molecular changes in cancer cells," Yaffe said. "In the future we will see other agents like this used...offering us much greater accuracy in finding cancers."

MBI is cheaper than magnetic resonance imaging (MRI), less than half the cost, and the images are easy to interpret, said Carrie Hruska, a biomedical engineer at the Mayo Clinic.

Researchers screened 940 women with both MBI and mammography. Thirteen tumours were detected in 12 patients. Eight of those were detected by MBI and one by mammography. Used together, MBI and mammography detected 10 tumours.

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

The next test will be to compare MBIs to MRIs. The United States government is paying for a new study, comparing the two in 120 high-risk women with dense breasts.

One drawback of MBI is that it uses about eight to 10 times more radiation than mammograms. Hruska and colleagues are trying to lower the dose with newer technology.

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

So far MBI screening is only available in certain cancer centres outside of Canada.