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MRI good indicator of size of ductal carcinoma lesions but does not contribute to negative margins, the study presented at the American Society of Breast Disease (ASBD) 34th Annual Symposium.

Although patients undergoing surgery for ductal carcinoma in situ began receiving preoperative magnetic resonance imaging scans (MRIs) around 2005 at some institutions, the success of the test to identify and predict the size of lesions does not correlate with negative surgical margins.

"A doctor can't feel the tumour with the hands in this type of cancer, so we rely on pathology and may not know for several days after the surgery whether we really got the whole area of cancer out," said Luisa C. Kropcho, MD, John Wayne Cancer Institute, Santa Monica, California.

About 30% to 50% of cases of in situ carcinoma turn into invasive cancer, noted Dr. Kropcho, in her presentation on April 16.

In the study, data were reviewed from a prospective database of 116 patients with in situ carcinoma between 2002 and 2009. Of those, 58 patients who received a preoperative MRI were compared with 58 patients who did not receive one. Size assessment by MRI was compared with pathological size, and the 2 groups were compared with respect to positive surgical margin rate. MRI measurement was most accurate in cases of high-grade in situ carcinoma, compared with low-grade and medium-grade cases, but no statistically significant difference was found in regard to positive margin rates.

"The strong correlation between size on the MRI and the final resulting tumour size didn't help us obtain negative margins at our institution. On the other hand, if the MRI is so accurate, why didn't we get negative margins?" asked Dr. Kropcho. "We will probably have to change our study's conclusion," she noted.

"You don't always have to get an MRI, because it hasn't been consistently shown that it makes a real difference. However, patients in some groups, such as women with genetic mutations, a family history, or hard to screen with mammography, should get an MRI," Dr. Kropcho said.

Dr. Kropcho explainged, Positive margins are an expensive problem and cause anxiety for the patient, as well as frustration for the surgeon. Ways of achieving more negative margins include taking more volume and bracketing, in which a little clip or needle is placed in the breast as a reference point.

Source: DG News

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