A Canadian study published last week in the New England Journal of Medicine found that women with highly dense breasts had a fivefold increase in breast-cancer risk. The study compared the mammogram results of 1,100 women over the course of eight years. Contributing to the risk is the fact that dense tissue and tumors both show up on mammograms as white areas, making it difficult to detect problems. Fat, on the other hand, appears dark and contrasts well with tumors.

“In a breast on a younger person, there’s a lot more fibers and glandular tissue and less fat,” says James Craft, a radiologist at the Medical College of Georgia, which was involved early on in Z-Tech’s study but was not privy to the latest data.

It’s for this reason that Nakashige believes Z-Tech has a chance of dethroning mammography as a screening tool, at least for this higher-risk population for which radiation is a concern and mammography is less effective.

Measuring electrical impedance in tissue is not a new field, but its application to breast-cancer screening only began to emerge as a research area in the early 1990s. That’s when Z-Tech founder Leslie Organ, then a visiting professor at the University of South Carolina, began to study the effects of electric current on malignant tissue.

Mirabel Medical [formerly TranScan], of Austin, TX, also began impedance research in the early 1990s. It is the first and only company to get Food and Drug Administration (FDA) approval to use electrical-impedance screening, but its system is limited to being an adjunct to mammography. Mirabel is currently testing a newer version of its system in a large multisite trial with the U.S. Army. The goal is to get FDA approval as a stand-alone screening tool.

Z-Tech is heading in the same direction. It plans to launch a screening product in Asia and Europe this and in Canada in 2008. A trial is in the works to achieve premarket approval in the United States.

Karina Bukhanov, head of breast imaging at Toronto’s Mount Sinai Hospital, a participant in the trial, is encouraged by Z-Tech’s impedance system but is equally cautious. “We need more studies,” she says. “Right now the numbers aren’t big enough to say with confidence that the sensitivity approaches that of mammography. It could, however, play a more critical role in remote areas where patients don’t have access to mammography.”