Murphy BL, et al. - Factors predicting positive margins at lumpectomy prompting intraoperative reexcision were identified in patients with breast cancer treated at a large referral center. When compared with invasive breast cancer, ductal carcinoma in situ was correlated with a higher rate of positive margins at lumpectomy on univariate analysis. Seed localization was associated with lower rates of margin positivity within the invasive disease.