February 12, 2006
Sunday

Four common noninvasive follow-up tests for breast cancer are not yet accurate enough to replace biopsies for women who have abnormal results from a mammogram or physical exam, a new review by government scientists concludes.

Health-care providers have increasingly turned to the noninvasive tests - ultrasound, MRI, PET scans and nuclear medicine scans - as an intermediate or alternative screening technique when initial tests suggest the possibility of breast cancer.

Only about one in five women who currently get either a surgical or needle biopsy after an abnormal mammogram or physical exam actually turns out to have breast cancer, meaning that 80 percent go through those procedures for what turns out to be no reason.

But the report from the federal Agency for Healthcare Research and Quality noted that relying instead on any of the four imaging tests in women with an average risk for breast cancer would miss about 4 percent to 9 percent of cancer cases in women testing negative, with potentially even more missed cancers among those in high-risk groups.

"Many women today undergo biopsies only to learn they do not have breast cancer," said Dr. Carolyn Clancy, director of the agency. "We do not want to be overly negative about these noninvasive tests; we hope they can improve so that in the future there will be a viable alternative to biopsy.

"But early and accurate diagnosis of breast cancer is crucial, and providers and consumers need to know that at this time, biopsies remain the most effective technique," Clancy added.

The report released Thursday involved analyzing 81 studies of the technologies in recent years. The report noted that many of the studies were not well enough designed or large enough to demonstrate that the techniques offered an effective alternative to biopsy.

"We are concerned and disturbed at the flaws in the evidence base on this question," said Maria Carolina Hinestrosa, vice president for programs and planning at the National Breast Cancer Coalition. "We need to pay closer attention to the quality of studies that are being funded, and consumers and payers need to question the use of these technologies before their benefit has been proven."

Clancy noted that the review was only aimed at assessing whether any of the noninvasive tests was accurate enough to be substituted for biopsy, not whether it was helpful in aiding diagnosis in breast-cancer patients. For instance, some doctors use one or more of the imaging systems to guide them to the right location for a biopsy, which can still miss cancer if the wrong tissue sample is studied.

"We know that biopsy is not perfect," Clancy added. "But it is a necessary step in order to begin treatment in a timely manner."

On the Net:

http://www.effectivehealthcare.ahrq.gov

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