Researchers claim that a radioactive tracer which "lights up" cancer hiding inside dense breasts is showing potential after its most important test against mammograms, being able to disclose more tumors and give a fewer number of false alarms.

Four studies regarding a new screening technique, which is hoped to make possible a better way to help detect breast cancer tumors, have been presented this week on The American Society of Clinical Oncology’s 2008 Breast Cancer Symposium, which is taking place in Washington D.C.

The tool, called molecular breast imaging (MBI), is only an experimental method. Therefore, it would not be used to substitute mammograms for people who don’t present a high risk of the disease, the second most common type of cancer after lung cancer. Still, the technique might be very helpful to women who have a denser breast tissue and whose disease can’t be detected by means of mammograms. An estimated 25 percent of women aged 40 years or over have dense breasts.

MBI is “a promising technology," according to Carrie Hruska, a biomedical engineer at the Mayo Clinic in Rochester, Minnesota, which has been working on it for a period of six years. “We're certainly not advocating replacing mammography in any way. But we think it (MBI) would have a role as an additional test for those women that aren't served as well by mammography as we would like," she said.

With the help of an injected radiotracer, MBI can spot variations in the behavior of cancer tissue as compared to the normal one, The Washington Post reported.

The study led by Hruska is the largest to date to compare MBI to mammography. Involving 940 women, it was partly financed by Bristol-Myers Squibb, the pharmaceutical corporation which provided the radioactive agent.

Researchers said that the molecular breast imaging spotted three times as many breast cancers in patients who had dense breasts and who were at a higher cancer risk: 10 of 13 cancers among 375 patients after a period of 15 months, compared to 3 out of the 13 that mammography was able to detect.

According to Dr. Eric Winer of Harvard Medical School and Dana-Farber Cancer Institute in Boston, between 10% and 15% of breast cancers are left undetected by mammograms, Reuters reported. "More and more we may be getting away from one-size-fits-all in terms of screening approaches, and instead think about screening approaches that are directed more to an individual women based on her risk and on the characteristics of her breasts," he told the media during a conference call.

By using low-dose X-rays in order to examine the human breast, mammograms gave false alarms in roughly 9% of individuals, in contrast with 2% less for MBI.

As stated by Carrie Hruska, the molecular breast imaging might be a lower-cost option. According to her estimations, a patient will pay approximately $500 to benefit from MBI’s advantages. Hruska also said she hoped the availability of the screening method would rise soon.