A large retrospective study reports that adding MRI to mammography before or immediately after surgery was not associated with reduced local recurrence or contralateral breast cancer rates among women with ductal carcinoma in situ (DCIS) of the breast that were treated with lumpectomy.

Some doctors order MRI routinely to look for additional areas of cancer and others use it to get more information if there is a discrepancy between what is found on physical exam and what they are seeing on a mammogram or an ultrasound.

The findings suggest that MRI does not improve long-term outcomes for most women with DCIS, and may lead to a decrease in routine use of MRI in this patient population.

“We now have a lot of evidence that indicates that MRI isn’t necessary for every patient with DCIS. Aside from the cost of the test, MRI has a rather high false positive rate, which may result in additional biopsies and a delay in surgery,” said first study author Melissa L. Pilewskie, MD, a breast surgeon at Memorial Sloan-Kettering Cancer Center in New York, NY and Commack, NY.

“We need to focus on spending money and time on tests that we know are going to provide benefit.”

There are no published clinical practice guidelines on the use of MRI in women with newly diagnosed breast cancer.

Therefore, overall use of MRI for patients with breast cancer varies by hospital and individual surgeon.

A recent survey of U.S. surgeons reported that 37 percent routinely use MRI for patients with DCIS.

Surgeons at academic institutions were less likely to refer patients with newly diagnosed breast cancer to MRI testing compared private practice surgeons.

Researchers evaluated locoregional recurrence rates among 2,321 women who underwent a lumpectomy for DCIS between 1997 and 2010 at Memorial Sloan-Kettering Cancer Center. In that cohort of patients, 596 had received an MRI either before or immediately after their surgery, and 1,725 had not. The women were followed for a median period of 59 months.

The differences in five-year locoregional recurrence rates were not statistically significant between those two groups of women (8.5 percent with MRI vs. 7.2 percent without MRI). The eight-year recurrence rates were also not significantly different (14.6 percent vs. 10.2 percent).

Even after controlling for patient characteristics and factors linked to risk of recurrence (age, menopausal status, family history, clinical presentation, use of adjuvant endocrine (hormonal) therapy or radiation, surgical margin status, and number of excisions), MRI was still not associated with lower locoregional recurrence rates.

Researchers also found no statistically significant differences in rates of contralateral breast cancer at five years (3.5 percent in both groups) or eight years (3.5 percent in the MRI group and 5.1 percent in the mammography only group).

Women who had an MRI were younger, more likely to be pre- or peri-menopausal, have a family history of breast cancer, and receive radiation and hormonal therapy.

Many of these factors are also associated with higher risk disease, which may explain a slightly higher recurrence rates in that group compared to those who did not have an MRI, while use of endocrine and radiation therapy decrease the risk of recurrence.

Dr. Pilewskie stated that one could also assume that the same risk factors prompted doctors to order an MRI for those patients.

Most women with DCIS who receive MRI around the time of surgery, have the scan before surgery to assess the extent of the disease. On occasion, a woman may have an MRI after surgery to look for any residual disease in the breast and/or plan for re-excision, if positive margins are found after lumpectomy. In this study, most women (81%) who had an MRI received it before surgery.

Previous studies have shown that use of MRI does not decrease re-excision rates for women with DCIS. Together with the present study, these findings indicate that MRI is not associated with improved short-term or long-term outcomes for these patients. According to Dr. Pilewskie, future research should focus on areas where use of MRI is likely to improve patient care and outcomes — such as monitoring the response to neoadjuvant chemotherapy — rather than in routine preoperative management of patients.

Source: ASCO