Prophylactic breast irradiation reduces background parenchymal enhancement (BPE) on MRI: A secondary analysis.

PURPOSE: We recently showed that prophylactic breast irradiation (PBI) reduces the risk of contralateral breast cancer in BRCA mutation carriers undergoing treatment for early breast cancer. It has been suggested that Background Parenchymal Enhancement (BPE) may be a biomarker for increased risk of breast cancer. METHODS: For participants in the trial we reviewed the MRI prior to enrollment and following radiation treatment and scored the contralateral breast for BPE and density. RESULTS: Significant reduction of BPE was more commonly noted following PBI (p = 0.011) compared to the control group. CONCLUSION: Reduction of BPE by PBI may contribute to its prophylactic effect.