Staging breast CA with MRI has advantages and disadvantages

The use of MRI to stage the affected breast in breast cancer leads to more extensive surgery in an appreciable percentage of women, and the rate of false positives is a cause for concern, according to research published online May 12 in the Journal of Clinical Oncology.

Nehmat Houssami, PhD, of the University of Sydney in Australia, and colleagues conducted a systematic review and meta-analysis of 19 studies including 2,610 women with breast cancer to examine the effects of breast MRI in detecting occult foci of disease distinct from the index cancer.

MRI detected additional disease in 16% of women, the researchers report. Sixty-six percent of these findings were confirmed as malignant by histology. Wide local excision was converted to mastectomy in 8.1% of cases and to more extensive surgery in 11.3% of cases in women with additional foci of cancer detected by MRI. Conversely, due to false positives, these numbers were 1.1% and 5.5%, respectively.

"The value of MRI should be judged after consideration of two factors (other than the additional cost of MRI, which is important but not within the scope of this review): the clinical benefit (if any) of this enhanced staging of the breast above baseline assessment, and women's and clinicians' views of the trade-off between true-positive and false-positive outcomes (both in detection and in conversion to more extensive surgery)," the authors write.

Houssami N, Ciatto S, Macaskill P, et al. Accuracy and surgical impact of magnetic resonance imaging in breast cancer staging: systematic review and meta-analysis in detection of multifocal and multicentric cancer. J Clin Oncol. 10.1200/JCO.2007.15.2108.