Melissa L. Pilewskie, MD
Patients with ductal carcinoma in situ (DCIS) who received an MRI added to mammography before or immediately after receiving a lumpectomy did not experience an improvement in the rate of disease recurrence, according to the results of a large, retrospective study (J Clin Oncol. 2013; [suppl 26; abstr 57]).
Although no published clinical guidelines currently exist for the use of MRI in patients with newly diagnosed breast cancer, the screening is often ordered to determine whether a clinician missed any areas of cancer or to determine if there was a discrepancy between a mammogram and a physical exam.
“Theoretically, treating this additional disease found by MRI could result in lower rates of local recurrence or contralateral breast cancer down the road,” said Melissa L. Pilewskie, MD, a breast surgeon at Memorial Sloan-Kettering Cancer Center (MSKCC) in New York City, and first author of the study.
Since no formal guidelines exist, the use of MRI in newly diagnosed patients varies widely among doctors and hospitals, although a recent survey of US surgeons found that 37% of them routinely use MRI for patients with DCIS. Pilewskie and colleagues hypothesized that this test may be unnecessary since studies have not shown decreased rates of re-excision, with some studies even reporting unnecessary increases in mastectomy rates.
In this study, researchers looked at locoregional recurrence (LRR) rates in women with DCIS and compared the rates in patients who received a perioperative MRI with those who did not. A prospectively maintained database at MSKCC included data on all women who underwent breast-conserving surgery for DCIS between 1997 and 2010, and identified 2321 cases for inclusion in the study. Of those cases, 596 received MRI and 1725 did not.
At a median follow-up of 57 months, there were 184 instances of ipsilateral breast tumor recurrence. The 5-year LRR rates were 8.5% in patients who received MRI and 7.2% in patients who did not, and this difference was not statistically significant (P = .52). At 8 years, LRR rates were 14.6% and 10.2%, respectively. When adjusting for age, menopausal status, family history, presentation, adjuvant ther-apy, margin status, number of excisions, and year of surgery, the researchers did not find that MRI was associated with lower LRR rates. This was also true for patients who received radiation therapy.
Additionally, the researchers looked at contralateral breast cancer event-free rates. At 5 years, both groups had the same event-free rates of 3.5%, and at 8 years, the rate in the group that received MRI was 3.5% compared with 5.1% in patients who did not receive MRI (P = .858).
In the entire cohort, patients who received an MRI did not experience a lower rate of events, whereas patients who received endocrine therapy and had a negative margin status did see improvements in their LRRs, which Pilewskie said was to be expected.
“We did not find an association between perioperative breast MRI and decreased rates of either locoregional recurrence or contralateral breast cancer,” Pilewskie said. “In the absence of evidence that MRI is improving our surgical management or, as we show here, long-term outcomes, the routine use of this test for DCIS should be questioned.”
Presently, guidelines for the use of breast MRI in the perioperative setting for treatment of DCIS are lacking. In this retrospective cohort study conducted by Melissa Pilewskie, MD, at Memorial Sloan-Kettering Cancer Center, perioperative breast MRI with DCIS did not reduce the rate of locoregional recurrence of breast cancer. Certainly, practical application of the use of breast MRI in this setting should be reconsidered.
Breast MRI can be a costly, difficult procedure for some patients and often results in an associated higher mastectomy rate. Some researchers hypothesize that the use of known, effective treatments for DCIS (radiation therapy, systemic endocrine therapy, and adequate surgical margin status) are effective at eradicating occult disease and that perioperative breast MRI does not contribute additional advantages to treatment.
The outcomes of this retrospective study are hypothesis-provoking, and additional randomized trials are needed to investigate whether breast MRI has a role in the management of DCIS.