MRI study points to use in finding breast cancer

The Nation

December 08, 2004|By Jonathan Bor | Jonathan Bor,SUN STAFF

Magnetic resonance imaging might play an increasingly important role in finding malignant breast lumps but isn't accurate enough to eliminate the need for biopsies, researchers said yesterday.

The technology, which is known as MRI and uses powerful magnets and radio waves to view soft tissues, detected cancers at a higher rate than traditional X-ray mammography in a study coordinated by the Johns Hopkins School of Medicine.

At 14 university hospitals in the United States and Europe, doctors performed MRIs and mammograms on 821 women who had already been referred for breast biopsies. Biopsies are considered definitive because surgeons withdraw a sample of breast tissue for examination under a microscope.

The MRIs identified 88 percent of the 404 cancers that turned up on the biopsies and correctly excluded as noncancerous 67 percent of the 417 masses that turned out to be benign.

False suspicions

Although the MRIs fared somewhat better than mammograms, the results show that they fail to detect all cancers and also raise a false suspicion of cancer in some cases.

The study appears in today's Journal of the American Medical Association, and follows recent studies in Canada and the Netherlands pointing to a role for MRI in high-risk patients.

Dr. David A. Bluemke, clinical director of MRI at Hopkins and lead author of the study, said the scans could be well-suited to women who have a family history of breast cancer and others who had cancer before and risk a recurrence.

MRIs could also be a better choice for young women who get confusing mammography results because their breast tissue is dense and fibrous. Such women are often sent back for repeat mammograms that show cloudy but ambiguous masses and for biopsies that turn out to be unnecessary.

"It's a very expensive test, and we want to use it in patients who will be at the most benefit," said Bluemke. "We don't see it being a screening test for the majority of patients, except those perhaps at the highest genetic risk."

Bluemke said he expects that 1 percent to 5 percent of women should receive MRIs for the detection of breast cancer.

Types of treatment

In an editorial accompanying the study, Dr. Monica Morrow of Fox Chase Cancer Center in Philadelphia said a more important question is whether MRIs can identify patients who can forgo radiation therapy after lumpectomy - surgery that removes the lump but not the whole breast.

Clinical trials are needed to determine whether the scans can reliably detect whether surgeons have removed all suspicious tissue - making painful radiation treatments unnecessary.

"The need for radiotherapy remains a major drawback to breast conserving therapy for many patients," she wrote. "Perhaps a more important issue is whether MRI will allow identification of a subset of patients who require no breast irradiation, or perhaps only partial breast irradiation."

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