HOT SPRINGS, VA. — Routine use of bilateral breast MRI before surgery may change the management of nearly 20% of candidates for breast conservation, lowering reexcision rates to achieve clear surgical margins, according to a retrospective study.
The ability to perform MRI-directed biopsies is a “critical component” of a program that uses preoperative MRI to locate breast cancer lesions, said Dr. William G. Cance at the annual meeting of the Southern Surgical Association.
Dr. Cance and his coauthors evaluated the ability of preoperative MRI scans to improve the selection of candidates for breast-conserving therapy, plan multimodality treatments more precisely, and improve cancer-related outcomes by identifying occult sites of disease at an earlier stage.
They reviewed a series of 79 consecutive candidates for breast conservation who underwent preoperative MRI scanning. The median age of the women was 57 years. Each patient received a physical exam, mammogram, ultrasound, and MRI during an 18-month period in 2006–2007, said Dr. Cance, chairman of the surgery department at the University of Florida, Gainesville.
Patients who had lesions that were suspicious for cancer on an MRI and confirmed on an ultrasound had an ultrasound-guided core biopsy. The lesions that were detected by MRI but not by ultrasound were biopsied under MRI guidance.
The results obtained on the initial MRI scan prompted an additional 25 biopsies in 21 patients. Positive results for cancer or ductal carcinoma in situ were detected in 3 of 6 ultrasound-guided biopsies and in 8 of 19 MRI-guided biopsies. Changes in treatment plans were necessary for 15 (19%) of the 79 patients, because of multicentric disease (7 patients), greater extent of the primary tumor (6), or contralateral breast cancer (2).
Breast-conserving therapy was contraindicated in patients with multicentric tumors in multiple quadrants of the breast or solitary tumors that were large relative to breast size.
In all, breast-conserving therapy was possible for 60 of the 79 patients. Of 61 lumpectomies performed in those 60 patients, 6 patients (10%) required reexcision for close or positive margins. These results compare favorably with other series, Dr. Cance said.
Receipt of an MRI did not significantly delay treatment. A median of 2 days passed between the initial surgical consult and the receipt of a bilateral breast MRI, while a median of 8 days occurred between the initial surgical consult and an MRI-directed biopsy.
Dr. Cance speculated that MRI scanning may lower reexcision rates for close or positive margins by improving the selection of patients for neoadjuvant chemotherapy, the selection of patients for partial versus total mastectomy, and the planning of the extent of partial mastectomy.
Patient selection is crucial for the best oncologic outcomes and cosmesis with breast-conserving therapy, he said. But even after efforts are made to characterize the tumor, locate it radiographically, and then excise it with clear surgical margins, “reexcision rates to achieve clear margins still remain high,” he said.
“The only prognostic factor that we as surgeons can affect is margin status,” Dr. V. Suzanne Klimberg of the University of Arkansas, Little Rock, said in a scheduled discussion of the study. “This paper demonstrates that preoperative MRI may help us select out those patients in which we would be unlikely to obtain negative margins.”
Although the investigators did not evaluate the costs of MRI scanning, Dr. Stephen R. Grobmyer, Dr. Cance's colleague at the University of Florida, suggested that the scans may save money in the long term by decreasing reexcision rates and recurrent disease. MRI scans and MRI-guided biopsies cost about $1,500 at the University of Florida, according to Dr. Grobmyer.
The MRI-directed biopsy has been shown to improve the accuracy of preoperative staging. It may be used in conjunction with a second-look ultrasound to confirm the extent of the disease seen on MRI or prevent overtreatment in the event of an MRI scan that is negative for disease, said Dr. Cance.
Bilateral MRI in a patient with multicentric breast cancer detected a primary lesion (left, in white) that was also found by mammography; MRI detected another invasive lesion (right) that was not revealed by mammography. Photos courtesy Dr. Stephen R. Grobmyer