You are here
Breast MRI screening of women at average risk of breast cancer: An observational cohort study.
Poster Session A: Risk Assessment, Prevention, Early Detection, Screening, and Local/Regional Therapy
Background: Breast-MRI is currently recommended for screening women at high-risk of breast-cancer only. However, despite decades of mammographic-screening, breast-cancer continues to represent a major cause of cancer-death also for women at average-risk – suggesting a need for improved methods for early diagnosis also for these women. Therefore, we investigated the utility of supplemental MRI-screening of women who carry an average-risk of breast-cancer. Methods: Prospective observational cohort-study conducted in two academic breast-centers on asymptomatic women at average-risk in the usual age range for screening-mammography (40 to 70). Women underwent DCE-breast-MRI in addition to mammography every 12, 24, or 36 months, plus follow-up of 2 years to establish a standard-of-reference. We report on the supplemental-cancer-yield, interval-cancer-rate, diagnostic accuracy of screening-MRI, and biologic profiles of additional, MRI-detected breast-cancers. Results: 2120 women underwent a total 3861 MRI-studies covering 7007 women-years. Breast-cancer was diagnosed in 61/2120 women (DCIS: 20, invasive: 41), and ADH/LIN in another 21. Interval-cancer-rate was 0%, irrespective of screening interval. Forty-eight women were diagnosed with breast-cancer at prevalence-screening by MRI alone (supplemental cancer-detection-rate: 22.6 per 1000); 13 women were diagnosed with breast-cancer in 1741 incidence-screening-rounds collected over 4887 women-years. A total 12 of these 13 incident cancers were diagnosed by screening-MRI alone (supplemental-cancer-detection-rate: 6.9 per 1000), one by MRI and mammography, none by mammography alone. Supplemental-cancer-detection-rate was independent of mammographic breast-density. Invasive cancers were small (mean size: 8mm), node-negative in 93.4%, ER/PR-negative in 32.8%, and de-differentiated in 41.7% at prevalence, and 46.0% at incidence-screening. Specificity of MRI-screening was 97.1%, False-Positive-Rate 2.9%. Conclusions: MRI-screening improves detection of biologically relevant breast-cancer in women at average-risk, and reduces the interval-cancer-rate down to 0%, at a low false-positive rate.