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Breast Magnetic Resonance Imaging in Early-Stage Breast Cancer: Is There Really No Value?

Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands

Petra H.M. Peeters

Departments of Clinical Epidemiology, Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, the Netherlands

Willem M.P.Th. Mali

Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands

Inne H.M. Borel Rinkes

Department of Surgical Oncology, University Medical Center Utrecht, Utrecht, the Netherlands

To the Editor:

We read the recent article by Solin et al¹ on the relation of breast magnetic resonance imaging (MRI) and outcome after breast-conservation treatment (BCT) with radiation in women with early-stage breast cancer with great interest. In this article, the authors present the results of a large retrospective, single center study, including 756 women with early-stage breast cancer of which 215 (28%) underwent breast MRI during work-up of their disease. The authors conclude that there is no difference in the rate of local recurrence, contralateral breast cancer, distant metastases, and survival between patients who underwent breast MRI and those who did not. More importantly, they state that use of breast MRI at time of diagnosis and evaluation for patients with early-stage breast cancer was not associated with improved outcome after BCT.¹

Because their conclusion may have important clinical consequences, we would like to address several methodological flaws in their study. We believe that caution with interpretation of their findings is warranted. First, also recognized by the authors, the study is a retrospective, single-center, cohort study. This indicates that the decision to perform preoperative breast MRI was made on a patient-to-patient basis, implying that potential selection bias is introduced. Because the authors did not describe why the 215 patients underwent breast MRI, we cannot exclude that these patients had denser breasts, higher breast cancer risk, or more extensive disease at the time of their original imaging studies, indicating that the group of patients that underwent breast MRI may have had a worse prognosis in the first place.

Second, we would like to address the fact that the authors included both preoperative MRIs and MRI examinations that were performed after lumpectomy in the analysis. The latter accounted for 50% of the analyzed MRI examinations in the study. The diagnostic performance of MRI directly after surgery is decreased: the required interval between breast surgery and MRI is considered to be 6 months.² We believe that if only the preoperative MRI examinations were included in the analysis, the effect of MRI would have become evident. Furthermore, the authors chose to begin follow-up at the start of radiation therapy. In our opinion, patients could benefit from preoperative breast MRI at an earlier stage in the therapeutic work-up. Because of the capacity of MRI to determine tumor extent more accurately than mammography,³ more accurate preoperative planning could be performed and the number of re-excisions could potentially be reduced by performing preoperative breast MRI. The authors state that 58% of patients underwent a re-excision, however, no information is presented on whether these patients underwent preoperative breast MRI. More importantly, the authors excluded patients that underwent a mastectomy because of extensive breast disease demonstrated on MRI. They state in their discussion that this could underestimate the beneficial effect of preoperative breast MRI. We agree with the authors, since a comparable study by Fischer et al⁴ demonstrated indeed that preoperative breast MRI does improve patient outcome, and pointed out that the preoperative decision to change the treatment strategy (ie, convert from breast-conserving surgery to mastectomy) is one of the advantages of performing preoperative breast MRI, apart from the lower local recurrent cancer rate.

Overall, the main drawback of Solin et al's¹ study is the nonrandomized study design. Usually, in clinical practice breast MRI is performed in the more complicated cases, which can bias the results and can underestimate the potential benefit of breast MRI. In our opinion, the definitive answer on the impact of breast MRI on patient outcome of BCT in patients with early-stage breast cancer can only be provided by a randomized controlled trial. In our institution and several affiliated hospitals, a randomized controlled trial evaluating the additional value of preoperative breast MRI in patients with nonpalpable breast cancer (the Mammography of Nonpalpable Breast Tumors trial) is currently running. The primary end point is to assess whether preoperative breast MRI influences the number of re-excisions and the number of conversions from BCT to mastectomy. The design of the study has recently been published.⁵ To date, 320 patients are included and we expect inclusion to be completed in the beginning of 2009. The results of this study will indicate whether there is really no value of preoperative breast MRI for patients with early-stage breast cancer.

AUTHORS' DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST

The author(s) indicated no potential conflicts of interest.

REFERENCES

1. Solin LJ, Orel SG, Hwang WT, et al: Relationship of breast magnetic resonance imaging to outcome after breast-conservation treatment with radiation for women with early-stage invasive breast carcinoma or ductal carcinoma in situ. J Clin Oncol 26:386-391, 2008

2. Fischer U: Indications for MR mammography: Practical MR Mammography. Stuttgart, Germany, Georg Thieme Verlag, 2004, pp 140-161

3. Schmitz AC, Meeuwis C, Veldhuis WB, et al: 3.0T MRI of infiltrating lobular breast cancer: Preoperative staging of patients referred with a single breast lesion and consequences for the surgical management. Breast J 14:206-208, 2008

4. Fischer U: Breast carcinoma: Effect of preoperative contrast-enhanced MR imaging on the therapeutic approach. Radiol 213:881-888, 1999

5. Peters NH, Borel Rinkes I, Mali WP, et al: Breast MRI in nonpalpable breast lesions: A randomized trial with diagnostic and therapeutic outcome - MONET - study. Trials 8:40, 2007

Related Reply

• In Reply
  Lawrence J. Solin, Susan G. Orel, Mitchell D. Schnall, Wei-Ting Hwang, and Eleanor E. Harris
  JCO 2008 26: 3466-3467 [Full Text]

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  Lawrence J. Solin, Susan G. Orel, Wei-Ting Hwang, Eleanor E. Harris, and Mitchell D. Schnall
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