Pre-operative breast magnetic resonance imaging (MRI) influences patient selection for partial breast irradiation

604 Background: Many patients with localized breast cancer undergo breast conservation therapy. Partial breast irradiation (PBI) is a technique that reduces irradiated tissue volume and decreases treatment time. Appropriate patient selection for this technique is critical. We studied the influence of pre-operative breast MRI on patient selection for PBI. Methods: Between 05/04 and 05/05, 231 women with newly diagnosed breast cancer underwent pre-operative bilateral breast MRI (median age = 64, range 34 to 89). Following initial clinico-pathologic review, patients were deemed to be eligible for PBI based on the NSABP B39 protocol if they satisfied its inclusion criteria (tumor size ≤3 cm, ≤3 positive nodes, negative surgical margins, lack of multicentric disease), derived through physical examination, mammography and/or ultrasonography. Breast MRI scans of all patients deemed eligible for PBI by these criteria were then reviewed to determine the impact of the MRI findings on their eligibility for PBI. Only...