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Cancer yield of mammography, MRI, and ultrasound in high-risk women enrolled in a prospective multi-institution breast cancer screening trial.

9626 Background: Several single institution trials suggest MRI and US may be beneficial in detecting clinically and mammographically occult cancer in women at high risk for breast cancer. However, few prior studies include both US and MRI in patient evaluation, and the range of added cancer yield of both modalities varies widely from <1% to >10%. This is the first North American, multi institution study of MRI, mammography and US.


METHODS
We conducted a prospective study of screening mammography, MRI and ultrasound in women ≥ 25 years of age who were genetically high risk, defined as BRCA1 or BRCA2 carriers or with at least a 20% probability of carrying a BRCA1/BRCA2 mutation as determined by BRCAPRO. In order to be eligible, women had to have a normal breast examination. All three imaging modalities were performed within 90 days of each other. Women were eligible if they were unaffected with cancer or had breast cancer but had completed adjuvant chemotherapy and radiation therapy at least six months prior to study entry.


RESULTS
A total of 195 women were enrolled in this study over a six month period and 171 completed all study exams (mammography, ultrasound and MRI). Sixteen biopsies were performed and six cancers were detected for an overall 3.5% cancer yield. MRI detected all six cancers while mammography detected two and US detected one. The diagnostic yields for each test were: MRI 3.5%, US 0.6%, and mammography 1.2%. MRI, US, and mammography resulted in biopsies being performed in 8.2%, 2.3%, and 2.3% patients, respectively.


CONCLUSIONS
Screening high risk women with mammography, MRI and US produced a 3.5% cancer yield. Screening MRI was associated with a higher biopsy rate, but was the only modality that detected all six cancers in our study. No significant financial relationships to disclose.