MRI Beats Mammograms at Spotting Early Breast Cancer

Mar. 23 -- FRIDAY, Aug. 10 (HealthDay News) -- MRI appears to be better than mammograms at finding breast cancer before it spreads, German researchers report.

However, despite the technology's advantages, its cost and a lack of people skilled at reading breast MRIs means it won't replace mammograms any time soon, experts say.

"MRI is more powerful and accurate for diagnosing pre-invasive breast cancer called ductal carcinoma in situ (DCIS)," concluded lead research Dr. Christiane Kuhl, from the Department of Radiology at the University of Bonn.

Her team published its findings in the Aug. 11 issue of The Lancet.

Most breast cancers arise from cells that build up in the inner lining of the milk duct, Kuhl explained. As long as this cancer is confined to the duct, it is considered benign and does not spread.

"If you identify breast cancer at this stage and remove it, the patient is healed -- always," she said. "Avoiding invasive breast cancer is even better than early diagnosis."

In the study, Kuhl and colleagues collected data on more than 7,300 women over five years. In addition to mammograms, the women were also given MRIs. The researchers wanted to see if MRIs could detect DCIS.

They found that among the 167 women who had a DCIS, 92 percent were found by MRI compared with 56 percent found by mammography.

Moreover, of the 89 women diagnosed with "high grade" DCIS -- the ones most likely to develop into cancer -- 98 percent were found by MRI, compared with 52 percent found by mammography. In addition, 48 percent were missed by mammography but found by MRI alone.

High-grade DCIS almost always becomes invasive and does so after a short time, Kuhl explained. "When it becomes invasive, it is biologically aggressive -- that means it kills," she said.

In contrast, low-grade DCIS usually remains within the duct and poses no threat. In fact, women can have low-grade DCIS for a lifetime with no ill effects, Kuhl said.

Also, MRI was not associated with many false positive findings. The positive predictive value of both methods was similar -- 55 percent for mammography and 59 percent for MRI, the researchers reported.