News Clipping Mammograms Versus MRIs for Detecting DCIS

by Katrina Kahl

A study published in the August 2007 edition of The Lancet suggests that MRIs may detect more ductal carcinoma in situ (DCIS) at a stage more likely to progress to invasive breast cancer (high-grade DCIS) than mammograms.1 With this in mind, the researchers for this study speculate that detecting more high-grade DCIS, rather than low-grade DCIS, may lead to less overdiagnosis of benign early-stage breast cancer. However, because the capacity to perform breast MRIs in the United States is low, the current usefulness of the information presented in this study is questionable.

For the study, researchers examined more than 7,000 women in Germany over the last five years using both MRI and mammograms. All the women were patients at the breast center at the University of Bonn Hospital and Medical School. Of 167 women found to have DCIS, mammography detected the condition in 93 of the women (56 percent), while MRI detected it in 153 of the women (92 percent). The researchers also report that the ability of MRI to detect DCIS (i.e., sensitivity) increased with a higher grade of DCIS, whereas the sensitivity of mammography decreased with a higher grade. Of the 89 cases of high-grade DCIS, mammography detected 46 of the cases (48 percent), while MRI detected 87 of the cases (98 percent).

Previous studies of MRIs to detect DCIS have consistently found that mammograms are better at detecting the condition. The researchers in the current study suggest that those studies were biased, because they did not use the specific criteria required for diagnosing DCIS with an MRI. Additionally, previous studies examined the use of MRI on women who already had a diagnosis of DCIS with mammography. Because mammograms are better at detecting low-grade rather than high-grade DCIS (the opposite of MRIs, according to this study), the women with high-grade DCIS that was missed by mammograms but may have been found by MRI were not included in the studies.

However, in the United States, radiologists skilled and experienced enough to use MRIs for breast cancer detection are in short supply. “MRI is not yet ready for use as a mass screening tool,” says Christiane Kuhl, the lead author of The Lancet study. “In order to evaluate the MRI scans, an experienced eye is needed.”

BCA’s executive director Barbara Brenner says, “This study was reported as useful for women. In fact, as the researchers noted, we don’t have the capacity to do in the United States what was done in Germany, and we won’t for some time.”

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1 Christiane K. Kuhl, et al., “MRI for Diagnosis of Pure Ductal Carcinoma In Situ: A Prospective Observational Study,” Lancet, 2007;370, August 11, 2007.

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