Biopsy Best to Confirm Breast Cancer Diagnosis

A breast biopsy is the preferred follow-up procedure to confirm a cancer diagnosis, even though several other test options exist and may be offered by physicians, according to a report from the Agency for Healthcare Research and Quality (AHRQ).

The AHRQ study compared the effectiveness of biopsy, long considered the "gold standard," with four other tests.

The other four tests were magnetic resonance imaging, or MRI; ultrasonography; positron emission tomography (PET) scanning; and scintimammography, or breast scan.

The report focuses on a very specific question, says AHRQ Director Dr. Carolyn M. Clancy. The researchers were addressing whether or not any of the other noninvasive tests sufficiently are accurate to diagnosis cancer or to rule it out.

Four Tests Studied Commonly Used
A biopsy is accurate but invasive, requiring the taking of a sample of breast tissue and analyzing it for signs of cancer in a lab. Because of this, researchers have been searching for noninvasive tests that would be as accurate.

The four tests assessed in the report, all suggested as substitutes for biopsies, were not as accurate as a biopsy overall.

The tests studied missed between 4 percent and 9 percent of breast malignancies in women at average risk, the report found, and probably would miss more cases than that among women at higher risk of the disease.

How accurate is accurate enough?

"Some experts say a test would have to miss fewer than 2 percent to be considered sufficiently accurate," says Dr. Clancy.

It is hard to pinpoint the exact accuracy of biopsies, but a study published last year in the Annals of Surgery found that the "false-negative" rate for one type of biopsy, called a "core biopsy," was 6 percent, according to Fran Visco, the first president and spokeswoman for the National Breast Cancer Coalition in Washington, D.C.

In the AHRQ report, the researchers found that the use of MRI missed 38 cancers for every 1,000 women; ultrasound missed 50 tumors for every 1,000 women; and PET scans missed 76 per 1,000 women.

Scintimammography, a nuclear medicine test method that uses a small amount of a radioactive substance and a scanner to detect cancer, missed 93 tumors for every 1,000 women.

Most Effective Tests Needed
The report on the four noninvasive tests is valuable, explains Visco.

"My interest in the 2006 AHRQ report focuses on the fact that we move these technologies into clinical practice when we don't have the data that show they are effective,” notes Visco. “That adds to healthcare costs and also doesn't serve women well."

Having access to solid data that proves a test is accurate will help women and the healthcare system, she says.

Dr. Clancy adds that the findings in this study provide good information for women to have additional conversations with their physicians.

If a physician suggests one of the alternate tests after an abnormal mammogram it would be reasonable to ask for a biopsy instead of these tests.

Always consult your physician for more information.