High cancer yield and positive predictive value: outcomes at a center routinely using preoperative breast MRI for staging.

OBJECTIVE

The purpose of our study is to report the outcomes at a center that routinely uses breast MRI for preoperative staging, regardless of lesion histology or patient characteristics.

MATERIALS AND METHODS

Five hundred ninety-two patients with recently diagnosed breast cancer who underwent staging with preoperative breast MRI between January 1, 2003, and April 30, 2007, were reviewed. Five hundred seventy patients comprised the analysis set. Patient age, breast density, index tumor histology, receptor status (ER, PR, and HER2), and lymph node status were recorded. Biopsy rates, positive predictive values (PPVs) of biopsy, and overall cancer yield were calculated and compared using the chi-square test across patient age, mammographic breast density, index tumor type, receptor status, and lymph node status.

RESULTS

Biopsy was recommended and performed for 152 of 570 (27%) patients found to have one or more suspicious lesions on MRI distinct from the index cancer. Sixty-seven of 152 women who underwent biopsy had additional cancers diagnosed, for a PPV of 44%. Overall, 12% (67/570) of women had otherwise occult cancers diagnosed by MRI, with 8% having additional sites or greater extent of ipsilateral disease and 4% having unsuspected contralateral cancer detected by MRI alone. No significant differences were found in the probability of detecting an occult cancer on the basis of patient age, breast density, index tumor characteristics, or lymph node status.

CONCLUSION

Breast MRI detects otherwise occult cancer with an overall added cancer yield of 12% and a high PPV of 44% when applied to a diverse population of patients with newly diagnosed breast cancer.