Balance shifts toward MRI for breast screening

Most arguments against wider use of breast MRI have been eroded. The modality should no longer be considered an adjunct to mammography, but a potential replacement. That was the hard-hitting message from the European Congress of Radiology 2008 Peter E. Peters honorary lecture, delivered by breast MRI proponent Prof. Christiane Kuhl.

"If a woman at average risk of breast cancer has [given] informed consent, and had the advantages and disadvantages of screening explained to her, [and] if she wants to undergo the most sensitive screening test available, then I dare to say that she should be offered MRI," said Kuhl, director of oncologic imaging and interventional therapy at the University of Bonn in Germany.

She shared her view that radiology is on the verge of deploying breast MRI for population-based screening. A prospective clinical study is now needed to assess the modality's efficacy in women at average risk of breast cancer, she said.

Despite advances in diagnostic technology and drug therapies, breast cancer remains the most frequent cause of cancer death in women. In Europe alone, about 375,000 new cases of breast cancer will be diagnosed each year, and almost 130,000 women will die of the disease.

If the disease is detected when it is still confined to the breast, the five-year survival rate is 98% and the 10-year rate over 90%, Kuhl said. Increased use of mammographic screening means more breast cancers are being spotted in the localized phase, but the technique is far from perfect. The average sensitivity of mammography is 40%, dropping to 36% in women with dense breast tissue.

Kuhl outlined the steady evolution of breast MRI from problem-solving tool to presurgical staging modality to surveillance screening technique. The American Cancer Society now recommends annual breast MRI for women with a moderately high (20%) lifetime risk of breast malignancy.

"There is not a big gap between a lifetime risk of 20% and the average lifetime risk of 10%," she said.

Suspect lesions can be examined, and even removed entirely, using powerful MR-compatible vacuum-assisted biopsy tools. Breast MRI has also confounded its critics by diagnosing ductal carcinoma in situ with greater sensitivity than mammography. Study data indicate that the sensitivity of MRI increases as the biological aggressiveness of DCIS increases, whereas for mammography, the trend is opposite.

"So we are left with one remaining argument against screening: Breast MRI is too expensive. I would agree that it is expensive, yes. But it is always a question of how you invest your money, and for what," Kuhl said. "Early diagnosis is our most effective weapon in the fight against breast cancer."

-By Paula Gould