Biopsy Best After Abnormal Mammogram

Feb. 9, 2006 -- Several tests for breast cancer haven't been shown to be accurate enough to replace a standard biopsy, states a government report.

The Agency for Healthcare Research and Quality (AHRQ) reviewed studies of four common noninvasive tests that can be used to detect breast cancer after a woman has an abnormal mammogram or abnormal breast exam. The four tests are:

• Positive Emission Tomograpy (PET) scans
• Magnetic Resonance Imaging (MRI)
• Ultrasonography (ultrasound)
• Scintimammography (mammogram enhanced by a radioactive tracer)

"We found that these tests, while reasonably accurate, could still miss a substantial number of cancers if used to try to avoid a biopsy," AHRQ director Carolyn Clancy, MD, told reporters, in a teleconference.

"The risk of missing a cancer is sufficiently high that we conclude that these tests should not routinely replace a biopsy," she says.

A standard breast biopsy is done using a needle or an incision to sample the suspicious area. Because they break the skin, these biopsies are considered invasive.

Missed Cancers

"The bottom line is that 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," Clancy says.

According to the report, the tests would miss about 4% to 9% of cancers in women of average risk for cancer, says Clancy. "This rate is potentially greater for women who are at a higher risk for cancer."

Clancy doesn't dismiss any of the tests. "The report is not intended to be overly negative about these tests. They're commonly and effectively used for other types of diagnostic imaging," she says.

"Our goal is to provide information for providers and consumers and other health care decision makers about their use as a substitute for biopsy," Clancy says.

Most Biopsies Don't Show Cancer

"Only about one in five women currently getting a biopsy for an abnormal mammogram or breast examination will be found to have breast cancer," Clancy says.

"This is significant, because it means some 80% of women with an abnormality suspicious for cancer must undergo the biopsy procedure even though they ultimately prove not to have cancer," she says.

"Accurate noninvasive tests could reduce the number of women needing to undergo a biopsy," Clancy says. Meanwhile, she advises women to talk to their doctors about their options after an abnormal mammogram or abnormal breast exam.

"Having an abnormal mammogram encompasses a wide range of potential risks, from 1% to over 90% risk of cancer. A woman needs to understand her individual risk and how the diagnostic alternatives can help manage this risk," says Clancy.