Impact of Preoperative Breast MRI in Breast Cancer

Seth Miller, MD,¹ Marlin Wayne Causey, MD,¹ Nicolas Cahanding, MD,² Tommy Brown, MD,¹ and Donald Smith, MD²

1. Department of General Surgery, Madigan Army Medical Center, Tacoma, Washington. 2. Department of Radiology, Madigan Army Medical Center, Tacoma, Washington.

Contact: Seth Miller, MD. E-mail This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Citation: Miller S, Causey MW, Cahanding N, Brown T, Smith D. Impact of preoperative breast MRI in breast cancer. J Surg Radiol. 2010 Jul 1;1(1). Download PDF Impact of Preoperative Breast MRI in Breast Cancer 1578 Kb Received: April 26, 2010; Accepted: May 31, 2010; Published: May 31, 2010 Copyright: © 2010 Surgisphere Corporation. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Contents - Introduction - Materials and Methods - Results - Discussion - References

Introduction

The use of magnetic resonance imaging (MRI) in the detection of breast disease has been debated since the introduction of this procedure in 1985.¹ Current screening guidelines suggest annual screening MRI for women with a lifetime breast cancer risk greater than 20% as defined by family history-dependent models;^2,3 however, clinical indications for dedicated breast MRI also include staging evaluation to define extent of cancer, evaluation for the presence of multifocal or multicentric cancer of the ipsilateral breast, and screening for disease in the contralateral breast.² Our study reviews the outcome of implementing a policy of routine bilateral breast MRI on all patients with a new diagnosis of breast cancer at a single institution. Emphasis was placed on identifying the prevalence of multifocal, multicentric, and contralateral breast disease that resulted in alterations in management.

Materials and Methods

A single-institution, retrospective electronic medical record review was performed. Patients included in this review were obtained from a prospectively collected cancer registry after receiving a diagnosis of breast cancer on tissue biopsy. This review included 81 patients who, from October 2007 to December 2009, underwent routine bilateral breast MRI after implementation of an institutional policy recommending routine breast MRI for all patients newly diagnosed with breast cancer. Patients obtaining breast MRI prior to this policy and patients obtaining breast MRI for indications other than new diagnosis of breast cancer on tissue biopsy were excluded from this study.

Data was collected on patient demographics, family history, genetic predisposition to breast cancer, mammogram and ultrasound findings, core needle biopsy findings, and the presence of multifocal, multicentric, or contralateral breast disease. Data was also collected on alterations in management that resulted from obtaining breast MRI. These alterations included additional breast biopsies and changes in surgical management. Descriptive statistical analysis was performed using PASWTM Version 18.0 (SPSS, Chicago, IL).

Results

Analysis was performed on 81 patients undergoing pretreatment breast MRI. The average age of the study population was 56.7 +/- 12.0 years (range 28 to 82 years). A family history of cancer was present in 12.3% of the patients, and a prior cancer diagnosis was present in 8.6% of the patients. The average time from initial diagnosis until pretreatment MRI was 14 days (+/- 1.1 days). Pathology findings included invasive ductal carcinoma (IDC) (58%), ductal carcinoma in situ (DCIS) (19.8%), invasive lobular carcinoma (6.2%), inflammatory breast cancer (1.2%), and other findings (14.8%). In the study population, 72 patients (89%) underwent a surgical procedure, with 34 patients (47%) undergoing mastectomy, and 38 patients (53%) undergoing breast conservation therapy (BCT).

Breast MRI identified new lesions not noted with mammography or ultrasound in 39 patients (48.1%). Of these, multifocal disease was seen in 21 patients (54%), multicentric disease in 10 patients (26%), and contralateral disease in 8 patients (20.5%) (Figure 1). In patients with new lesions, the final pathologic diagnosis was IDC in 23 patients (59%), DCIS in 6 patients (15.4%), invasive lobular carcinoma in 3 patients (7.7%), and other diagnoses in 7 patients (17.9%).

When a new lesion was identified by MRI, the new lesion was sampled via radiographically-guided biopsy in 31 patients (79.5%). Surgical management was altered, either by conversion from BCT to mastectomy or by extending resection margins, in 22 patients (56.4%) (Figure 2). One patient, in addition to a focus of invasive lobular neoplasia, had a suspicious lesion in the contralateral breast. Pretreatment MRI indicated that the lesion was radiographically benign and thus the patient avoided invasive tissue biopsy in the contralateral breast. The introduction of pretreatment MRI resulted in additional biopsies in 38% of patients and alteration of surgical management in 27% of patients. Diagnostic imaging was also altered for some patients: a second-look ultrasound was completed in 64.1%, repeat MRI in 2.6%, and no further imaging in 33.3%.

Figure 1. (A) MRI confirmed the findings of a suspicious annual mammogram with subsequent ultrasound guided biopsy that demonstrated Invasive Lobular Carcinoma (B) in two distinct locations in the left white arrow). (C) MRI demonstrated an additional 4mm focus of enhancement in the contralateral breast (9 o’clock, white arrows) that was subsequently biopsied under ultrasound guidance (D, white arrows) and pathologic evaluation demonstrated low/intermediate grade DCIS (E).

Figure 2. (A) A 45 year old female underwent initial screening ultrasound. (B) She was called back for additional diagnostic mammogram that demonstrated suspicious cluster microcalcifications in the right breast (white arrows). (C) Stereotactic core needle biopsy demonstrated high nuclear grade DCIS (D) with comedo necrosis (white arrow). (E) Bilateral breast MRI demonstrated right breast lower outer quadrant segmental clumped enhancement (white arrows). (F) Ultrasound guided biopsy confirmed the MRI findings of additional foci of occult multifocal DCIS (G) and a larger surgical biopsy with negative margins was obtained.

Discussion

Several benefits of breast MRI are cited in the literature. The most significant advantage is increased sensitivity of MRI which, in 10-30% of patients, detects foci of cancer not seen on other imaging tests.4,5 Breast MRI has a sensitivity of 85-100% for breast cancer as a whole, and a sensitivity for invasive ductal carcinoma of 100%.⁶ Due to its improved sensitivity, the use of MRI screening in high risk patients is widely recommended and has been supported by multiple prospective trials.^2,3,7-9

While consensus has developed as to the use of breast MRI in high risk patients, the use of breast MRI for staging evaluation to define extent of cancer and identify synchronous lesions (Grade 2B Recommendation by the NCCN)2 remains controversial. Multiple studies have demonstrated changes in treatment plans based on preoperative MRI findings that range from 14% to 29%.^10-14 Surgical changes most often cited included conversion of BCT to mastectomy and performing wider excisions.^10-12 Alterations in treatment plans are assumed to be beneficial to the patient (i.e. based on true positive results on MRI); however, this is not always the case. A meta-analysis performed by Houssami and colleagues, including 19 studies and 2,763 patients, demonstrated additional disease on 16% of breast MRIs.¹⁵ For patients with true multifocal or multicentric disease, wide-local excision (WLE) was converted to mastectomy in 8.1% and to a more extensive procedure in 11%. More extensive surgery was, however, also seen in patients with false positive MRIs with conversion rates from WLE to mastectomy or to a more extensive surgery in 1.1% and 5.5%, respectively.¹⁵

Our study focuses on implementing a policy of routine bilateral breast MRI on all patients with a new diagnosis of breast cancer. In implementing a new policy, there may be a tendency to recommend more frequent intervention than that seen in the literature (38% compared to 14% to 29%).10-14 The MRI findings lead to more extensive surgery in 25% of the study patients, and additional biopsies were performed in over 33% of patients. While the effect on survival due to more extensive surgery is not known, the fact that BCT has been demonstrated to have survival equivalence to mastectomy¹⁶ suggests that routine MRI in average risk patients may lead to unnecessarily more extensive surgery. Additional biopsies prompted by MRI findings, however, can be performed at the time of MRI and would avoid additional appointments for further biopsies, minimize time to diagnosis, and minimize delay to surgery.

The overtreatment of breast cancer is not the only argument against routine breast MRI in newly diagnosed breast cancer. Bleicher and colleagues have also cited delays in time to surgery associated with pretreatment MRIs,¹⁷ though this delay may not be clinically significant. Our results show an average time of only 14 days between diagnosis and MRI. This is a minimal delay to time of surgery that is unlikely to affect overall survival, disease-free survival, and local recurrence.¹⁸

An additional impediment to the use of breast MRI is the cost. While MRI has been demonstrated to be cost-effective in BRCA1/2 positive patients,¹⁹ its cost-effectiveness in moderate and average risk patients is debated, and some groups of high risk breast patients still do not derive enough benefit to reach cost-effectiveness.²⁰ Additional cost-saving predictions, such as the proposed decrease in number of reoperations due to adequate initial resection based on MRI, have not borne out.²¹ Despite these findings, we were able to identify one patient in our study who avoided unnecessary surgery after pretreatment MRI. The number of patients avoiding unnecessary procedures may be underrepresented in the literature and could affect the cost-benefit analysis. Furthermore, the relative high incidence of contralateral disease seen in this study suggests that incidence of contralateral breast disease should be a factor in cost-analysis as performing bilateral breast surgery under a single general anesthetic could potentially save money and time in the long term. Finally, tailoring the use of pretreatment MRIs to patients at higher risk of breast cancer may improve the benefit to patients while minimizing costs.

Screening breast MRIs have been demonstrated to be beneficial in high-risk patients; however, the use of routine pretreatment breast MRIs after diagnosis of breast cancer remains controversial. This study identified new lesions in nearly half of the patients studied resulting in significant changes in management. This study suggests that further research into the role of pretreatment breast MRIs is warranted.

Disclosures

The investigators have adhered to the policies for protection of human subjects as prescribed in 45 CFR 46. The views expressed are those of the authors and do not reflect the official policy of the Department of the Army, the Department of Defense or the U.S. Government.

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