Breast cancers detected by breast MRI screening and ultrasound in asymptomatic Asian women: 8 years of experience in Taiwan.

Background: This study investigated one-stop breast screening combining magnetic resonance imaging (MRI) and ultrasound (US) in asymptomatic Asian women.

Methods: 3,586 asymptomatic women (mean age, 45.3 years) were retrospectively analyzed by breast MRI followed by US. US-guided biopsy was performed when the MRI-detected lesion was confirmed by US. When the lesion was not detected on the initial US, a second-look US guided by MRI findings was performed. Then biopsy was done. MRI-positive and US-negative patients were followed up according to MRI lesion size, MRI lesion morphology, and mammographic diagnosis.

Results: In total, 115 subjects had suspicious malignant lesions and received US-guided biopsy, and 47 malignant lesions, including 35 invasive cancers and 12 carcinoma in situ (CIS) lesions, were diagnosed. More than half (22/35, 63%) of the women with invasive cancer were <50 years of age, and 27 (57.4%) of the 47 cancer cases had early breast cancers. Two invasive cancers (5.7%) and 7 CIS lesions (58.3%) were found at the second-look US. The overall cancer incidence was 1.31% (47/3,586) and increased to 2.2% (78/3,586) if precancerous lesions were included. Subjects aged 41-50 years had the highest incidence of cancer detection (1.97%). Five MRI and US-negative cases had cancers found 1 year after the screening.

Conclusions: The results from the one-stop breast screening in this study showed that combining MRI and US is an efficient multimodality tool for screening asymptomatic Asian women in a metropolitan area of Taiwan who had concerns about the diagnosis and radiation of mammography.