Molecular breast imaging superior for at-risk women with dense breasts

NEW YORK (Reuters Health) - A relatively new screening technique called molecular breast imaging (MBI) is significantly more effective than mammography at detecting breast cancer in women at high risk for the disease who have dense breast patterns on mammography, according to research presented Wednesday at a press briefing ahead of the 2008 Breast Cancer Symposium.

"Women with dense breasts and those at increased risk for breast cancer are not served well by mammography. MBI's ability to detect cancer does not seem to be affected by mammographic density," lead researcher Dr. Carrie B. Hruska, from the Mayo Clinic, Rochester, Minnesota, reported.

Prior studies have shown that MBI -- which relies on the functional uptake of a radiotracer in breast tissue that preferentially accumulates in abnormal cells -- can reliably detect small breast tumors, even in mammographically dense breasts.

In their latest study, which is ongoing, Dr. Hruska and colleagues are analyzing findings on screening MBI and screening mammography (film or digital) in 940 high-risk women with mammographically confirmed dense breasts.

Thus far, a total of 13 cancers have been detected in 12 patients. "Screening mammography detected 3 out of 13 cancers, whereas MBI detected 10 out of 13 -- more than three times as many," Dr. Hruska noted. The combination of both techniques detected 11 of 13 cancers.

In 375 women who have completed 15 months of follow-up, MBI had a significantly higher sensitivity (75% versus 25% for mammography), while maintaining a nearly equivalent specificity (93.2% for MBI versus 91.3% for mammography). "MBI detected more cancers than screening mammography but it did not produce more false-positive results," Dr. Hruska explained.

MBI also had a lower recall rate than mammography (7.7% versus 9.4%). "Although MBI prompted more biopsies, its positive predictive value, or the number of biopsies that resulted in cancer, was much higher - 28% versus 18%," according to Dr. Hruska.

"MBI," the investigator concluded, "has shown great promise as a valuable adjunct to screening mammography for women who have dense breasts on mammography and are at increased risk of developing breast cancer."

The team's next step is to compare MBI prospectively to other screening methods, such as breast MRI.

The Breast Cancer Symposium, which gets underway Friday in Washington, D.C., is co-sponsored by the American Society of Breast Disease, the American Society of Breast Surgeons, the American Society of Clinical Oncology, the American Society of Therapeutic Radiology and Oncology, the National Consortium of Breast Centers, Inc., and the Society of Surgical Oncology.

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