From the Screening and Test Evaluation Program, School of Public Health, The University of Sydney, Sydney, New South Wales, Australia
Author's disclosure of potential conflicts of interest are found at the end of this article.
Address reprint requests to Nehmat Houssami, MPH, PhD, Screening and Test Evaluation Program, School of Public Health, Faculty of Medicine, The University of Sydney, Room 327, Public Health A27 (STEP), Sydney, NSW 2006, Australia; e-mail: nehmath{at}health.usyd.edu.au
Overview: This review updates the evidence on magnetic resonance imaging (MRI) in the preoperative evaluation of women with newly diagnosed breast cancer, focusing on the detection of additional cancer foci (occult on conventional imaging), and MRI-attributable effects on surgical treatment. Meta-analyses have estimated MRI's incremental detection for the affected breast as 16% (upstaged to multifocal and/or multicentric cancer). MRI is also associated with false positive detection (pooled estimate for MRI-only detection of true positives to false-positives is 1.9:1; positive predictive value [PPV] = 66%). Pooled estimates for MRI's effect on surgery are: (A) 11.3% for breast conservation changed to more extensive surgery (mastectomy or wider resection); and (B) 5.5% for breast conservation changed to more extensive surgery (mastectomy, wider resection, or additional surgical biopsy) as a result of false positives. Although the effect of MRI is clearly a change to more radical surgery than planned on the basis of conventional assessment, the implications of this change in care are unclear. In terms of surgical planning, initial data from a randomized trial show that preoperative MRI does not reduce re-excision rates; similar outcomes are reported in nonrandomized studies. Evidence on MRI of the contralateral breast for women with newly diagnosed (ipsilateral) invasive cancer indicates that MRI has an incremental cancer detection rate of 4.1% (95% CI: 2.7%, 6.0%), but a low- to moderate PPV of 47.9% (95% CI: 31.8%, 64.6%) — the latter of which is a significant limitation in this setting. The majority of MRI-detected contralateral cancers are early-stage tumors.
