Is there a role for routine screening MRI in women with LCIS?

Women with lobular carcinoma in situ (LCIS) have an elevated breast cancer risk, yet the benefit of MRI screening is unclear. We examined cancer detection rates with mammography alone versus mammography plus MRI in this high-risk population. From a prospectively maintained, single-institution database, we identified 776 patients diagnosed with LCIS after the adoption of screening MRI in April 1999. In addition to annual mammography and breast exam, MRI was used at the discretion of the physician and patient. Kaplan-Meier methods and landmark analyses at 1, 2, and 3 years following LCIS diagnosis were performed to compare rates of cancer detection with or without MRI. MRI screening was performed in 455 (59 %) patients (median, 3/patient). Median time from LCIS diagnosis to first MRI was 9 months (range 0.3-137 months). Patients undergoing MRI were younger (p < 0.0001), premenopausal (p < 0.0001), and more likely to have ≥1 first-degree relative with breast cancer (p = 0.009). At a median follow-up of 58 months, 98/776 (13 %) patients developed cancer. The crude cancer detection rate in both screening groups was 13 %. MRI was not associated with earlier stage, smaller size, or node negativity. Landmark analyses at 1, 2, and 3 years after LCIS diagnosis failed to demonstrate increased cancer detection rates among women having MRI (p = 0.23, 0.26, and 0.13, respectively). Although a diagnosis of LCIS remains a significant risk factor for breast cancer, the routine use of MRI does not result in increased cancer detection rates (short-term), nor does it result in earlier stage at diagnosis, illustrating the importance of defining optimal screening strategies for high-risk patients based on tumor biology rather than numerical risk.