Four common non-invasive tests for breast cancer are not accurate enough to routinely replace biopsies for women who receive abnormal findings from a mammogram or physical examination, according to a study released today by HHS' Agency for Healthcare Research and Quality (AHRQ).

Today's report is the second from AHRQ's new Effective Health Care Program, which compares the effectiveness of different treatments for health conditions. The report finds that each of the four tests-magnetic resonance imaging, ultrasonography, positron emission tomography scanning, and scintimammography--would miss a significant number of cases of cancer, compared with immediate biopsy for women at high-enough risk to warrant evaluation for breast cancer.

Mammography and physical examination are both used to detect the possibility of breast cancer. A woman receiving an abnormal mammogram or physical examination needs further confirmation to determine whether cancer is present. Currently, confirmation is recommended through a tissue biopsy, either by surgical excision or needle sampling.

Only about one in five women currently getting a biopsy for an abnormal mammogram or breast examination has breast cancer. The need for confirmation of the mammogram means some 80 percent of women with an abnormal mammogram must undergo the biopsy procedure, even though they ultimately prove not to have cancer. Accurate noninvasive tests could reduce the number of women needing to undergo a biopsy.

However, AHRQ's Comparative Effectiveness Review, Effectiveness of Noninvasive Diagnostic Tests for Breast Abnormalities, indicates that four common tests would miss about 4 percent to 9 percent of cancer cases among women testing negative who have average risk for the disease, with potentially more missed cancers among women at higher risk.

"So many women today undergo biopsies only to learn they do not have breast cancer. Hopefully, noninvasive tests can continue to improve so that in the future, there will be a viable alternative to biopsy," said AHRQ Director Carolyn M. Clancy, M.D. "But early and accurate diagnosis of breast cancer is crucial, and at this time, biopsies remain the most effective technique when mammography or physical examination reveals a potential problem."

The four tests reviewed in the study, and their results, were:

-- Magnetic resonance imaging (MRI) - MRI images are created by recording signals generated after radio frequency excitation of nuclear particles exposed to a strong magnetic field. Typically for breast imaging, dedicated breast coils (used to generate the magnetic field) are used - a woman lies prone with her breasts in close proximity to the coils. A contrast agent is given intravenously to highlight concentrations of blood vessels (e.g. around a tumor). For every 1,000 women who had a negative MRI, about 962 would have avoided an unnecessary biopsy, but 38 would have missed cancers.

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