MRI detects more breast cancers, but still with too many false positives

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The utilization of MR for breast imaging results in more surgical interventions, as it can detect additional disease; however, more work remains to be done to decrease the modality's false-positive (FP) detection rate according to research recently published in the Journal of Clinical Oncology.

Nehmat Houssami, PhD, from the School of Public Health at the University of Sydney in Australia, and colleagues conducted a systematic review and meta-analysis of the accuracy of MRI in detection of multifocal and/or multi-centric cancer not identified on conventional imaging.

The researchers estimated summary receiver operating characteristic curves, positive predictive value, true-positive (TP) to false positive (FP) ratio and examined their variability according to quality criteria. They calculated the pooled estimates of the proportion of women whose surgery was altered.

The investigators found that data from 19 studies, evaluating 2,610 cases, showed MRI detects additional disease in 16 percent of women with breast cancer. MRI incremental accuracy differed according to the reference standard, decreasing from 99 percent to 86 percent as the quality of the RS increased, the authors wrote.

Summary PPV was 66 percent and TP:FP ratio was 1.91, according to researchers.

Houssami and colleagues found that the conversion from wide local excision (WLE) to mastectomy was 8.1 percent from WLE to more extensive surgery was 11.3 percent in multifocal/multi-centric disease. Due to MRI-detected lesions (in women who did not have additional malignancy or histology) conversion from WLE to mastectomy was 1.1 percent and from WLE to more extensive surgery was 5.5 percent.

The authors concluded that randomized trials are needed to determine the clinical value of detecting additional disease which changes surgical treatment in women with apparently localized breast cancer.