MRI Detection of Otherwise Occult Malignancies in Women Recently Diagnosed with Breast Cancer.
Authors: Lehman C. , Lehman C. , Silbergeld J. , Silbergeld J. , DeMartini W. , DeMartini W. , Eby P. , Eby P. , Gutierrez R. , Gutierrez R. , Peacock S. , Peacock S. , Javid S. , Javid S. 
Published: December 2010

Objective. Breast Magnetic Resonance Imaging (MRI) is recommended as a screening test for women at high risk for breast cancer but its role as a diagnostic tool for women recently diagnosed with breast cancer is not universally accepted. We report outcomes in a center that routinely uses breast MRI to evaluate extent of disease in patients recently diagnosed with breast cancer.Material and Methods. Between 1/1/2003 and 4/30/2007, 592 patients with recently diagnosed breast cancer underwent bilateral breast MRI to assess extent of disease. All had undergone mammography prior to breast MRI. Twenty-two were excluded because they were either lost to follow up (n=7) or had a mastectomy or lumpectomy (n=15) where correlation of pathology to the study lesion was not possible or incomplete. 570 patients comprised the analysis set. Patient age, index tumor characteristics (histologic subtype, grade, ER/PR status, HER2 status and presence of angiolymphatic invasion), axillary lymph node status, and pathologic stage were recorded in addition to mammographic breast density. All MR exams were coded following the American College of Radiology Breast Imaging-Reporting and Data System (BI-RADS) breast MRI lexicon. Biopsy rates, positive predictive values of biopsy, and overall yield of detecting an occult cancer in the ipsilateral or contralateral breast were calculated and compared using Chi-square test across patient age, mammographic breast density, index tumor type, receptor status and presence or absence of lymph node metastases.Results. The distribution of tumor histologies was typical of that seen in the U.S. during the study period, with 61% having invasive ductal index cancers, 21% pure ductal carcinoma in situ, 19% invasive lobular or other invasive cancers and 67% being node negative at time of diagnosis. Additional biopsy was recommended for 152/570 (27%) patients found to have one or more suspicious lesions on MRI distinct from the index cancer, based upon mammographic, sonographic, or clinical exam measurements. Of the 152 women who underwent biopsy, 67 women had additional cancers diagnosed, for a positive predictive value of 44% (67/152). Overall, 12% (67/570) of women had otherwise occult cancers diagnosed by MRI alone: 8% of women had additional sites or greater extent of ipsilateral disease and 4% of women had unsuspected contralateral cancer detected by MRI alone. No significant differences were found in the probability of detecting an occult cancer based on patient age, breast density, index tumor characteristics, or lymph node status.Conclusion. The 12% added cancer yield of MRI in detecting additional ipsilateral or contralateral malignancies in a clinical population of women recently diagnosed with breast cancer is significantly higher than the added cancer yield of MRI screening among women at high risk for breast cancer. The positive predictive value of MRI in this clinical setting is also high, with 44% of women who undergo additional tissue sampling being diagnosed with otherwise occult cancer. The probability of finding additional malignancy does not vary significantly with patient age, breast density, or index cancer characteristics.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4017.