While MR scans can pick out potentially deadly breast cancers mammograms and even ultrasound exams might miss, many women opt to stay away, according to a new study.

In a paper published this week in Radiology, almost half of all women at increased risk for breast cancer who were offered an MR screening chose not to do it.

The study followed 1,215 women who were at heightened risk for breast cancer at more than a dozen health care centers in the United States, Canada and Argentina. It found that only around 58 percent of these women eligible for MR scans enrolled for the exam.
Of the 42 percent who refused, a plurality, or about a quarter of refusers, listed claustrophobia as their reason for staying away. Other top concerns were not having enough time (about one in five) and not being able to afford it (about one in ten).

And of the 58 percent who actually went in for the exam, almost 10 percent didn't complete it or wouldn't schedule a follow-up scan after their screening got botched by a technical problem.

"So it was closer to around 50 percent who got a good quality MRI, which is low for a screening test," Wendie Berg, M.D., Ph.D., a radiologist at Johns Hopkins Green Spring in Lutherville, MD, and first author of the paper, tells DOTmed News.

At-risk women

The study was an offshoot of the American College of Radiology Imaging Network (ACRIN) 6666 Protocol designed to see how effective supplemental screenings were in catching breast cancer in women with an elevated lifetime risk.

For this trial, all women were at least at intermediate risk for the disease because of personal or family history of the cancer or an atypical or high-risk biopsy result. And all had dense breasts.

But there were also women with a greater lifetime risk, such as known or suspected carriers of the BRCA1 or BRCA2 genes. Interestingly, women in this group, those who have a one-in-two to one-in-four lifetime chance of coming down with the disease, were more likely to see the study through to the end and get the MR scan.

And it makes sense, too. According to a study just presented by Dr. Berg at RSNA 2009, MR scans find cancers that mammograms and ultrasound miss. Because MR scans can image the tumor's vascularity, they can help detect growths in women with dense breasts as well as those who are BRCA1 carriers, a population in which mammography often fails to find early cancers.

As a result of evidence like this, two years ago the American Cancer Society recommended supplementing traditional mammographic screening with MR scans for high-risk women.

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