NO SURVIVAL BENEFIT OF PREOPERATIVE MRI IN WOMEN WITH DCIS

Routine use of MRI before or after surgery in women with ductal carcinoma in situ (DCIS) is not likely a sound clinical strategy because it does not improve long-term outcomes, according to a new single-center study.

The retrospective study, conducted by researchers from the Memorial Sloan-Kettering Cancer Center in New York City, suggests that MRI offers no advantage over standard imaging (mammography with or without ultrasound) in DCIS patients.

"The benefit of perioperative MRI for DCIS remains uncertain," conclude lead author Melissa Pilewskie, MD, and colleagues.

"Currently, there are no guidelines for the use of MRI in the work-up of women with DCIS," Dr. Pilewskie told reporters at a presscast in advance of the 2013 Breast Cancer Symposium, which will be held later this week in San Francisco. The presscast was organized by the American Society of Clinical Oncology (ASCO), which is sponsoring the symposium along with 5 other professional bodies.

About one third of surgeons in the United States will order an MRI for women with DCIS, she said.

"There's been a tremendous increase in the use of MRI, perioperatively and postoperatively, in invasive and noninvasive breast cancer," said Steven O'Day, MD, from the Beverly Hills Cancer Institute in Los Angeles, who moderated the presscast. He is also an ASCO spokesperson.

Theoretically, using MRI around the time of surgery in patients with DCIS can help find additional areas of disease, especially in women treated with lumpectomy alone, Dr. Pilewskie explained.

The researchers identified 2321 women who had undergone lumpectomy for DCIS between 1997 and 2010 at Memorial Sloan-Kettering. Of these patients, 596 received an MRI either before or immediately after surgery and 1725 did not.

After 5 years, local recurrence rates were not significantly different between the MRI and no-MRI groups (8.5% vs 7.2%; P = .52). After 8 years, the lack of a statistically significant difference held (14.6% vs 10.2%). Even after controlling for 9 patient variables, such as age, menopausal status, family history, and use of radiation or endocrine therapy, there was no significant difference in risk for local recurrence.

This multivariable analysis is important because women who undergo MRI will typically have a higher risk profile, and that was the case in this study, explained Dr. Pilewskie.

The fact that the women who underwent MRI had more risk factors might explain the slightly higher recurrence rates in that group than in the group that underwent only standard imaging, Dr. Pilewskie said in a press statement.

Contralateral Breast Cancer Findings

The study included another end point: the development of contralateral breast cancer in the study participants. "MRIs look at both breasts," Dr. O'Day noted.

But again, the results showed that there was no statistically significant difference in this end point. Contralateral breast cancer rates in the MRI and no-MRI groups were the same at 5 years (3.5% vs 3.5%) and similar at 8 years (3.5% vs 5.1%).

In the subgroup of patients who did not receive radiation therapy, MRI was not associated with improved long-term outcomes for either contralateral breast cancer or local regional recurrence.

The "routine use" of MRI did not improve these 2 outcomes in this retrospective study, summarized Dr. O'Day.

However, he did not discount any use of MRI in DCIS patients. "It's not that MRI can't be used," he explained. "There are cases where it is important to obtain information perioperatively or postoperatively with the additional sensitivity that MRI may give."

However, "this is an important study to ground us," Dr. O'Day added. Further prospective study is needed to refine the use of MRI, he said.

Dr. Pilewskie has disclosed no relevant financial relationships. Dr. O'Day reports acting as consultant or advisor for Bristol-Myers Squibb, Delcath, Eisai, Genentech, GlaxoSmithKline, and Roche; accepting honoraria from Bristol-Myers Squibb; and receiving research funding from Bristol-Myers Squibb, Eisai, GlaxoSmithKline, Lilly, and Roche/Genentech.

2013 Breast Cancer Symposium: Abstract 57. To be presented September 7, 2013.