A prospective study of tumor and technical factors associated with positive margins in breast-conservation therapy for nonpalpable malignancy

BACKGROUND: The purpose of this study was to identify factors that predict an increased risk of a positive surgical margin after breast-conserving therapy for nonpalpable carcinoma of the breast. METHODS: In this prospective study, 305 patients with nonpalpable invasive breast cancer or ductal carcinoma in situ were identified and underwent localization lumpectomy. Patient, technical, and tumor factors with a potential to predict margin status were documented. RESULTS: A 20% positive margin rate was observed. Univariate analysis of patient, tumor, and technical factors revealed that localizations performed under stereotactic guidance (P < .001), presence of in situ disease, high tumor grade, larger tumor size, multifocal disease, and presence of mammographic microcalcifications (P < .02) were predictive of positive margins. With the exception of tumor grade and mammographic microcalcifications, multivariable analysis identified the same factors. CONCLUSIONS: This study identified several factors associated with positive margins that should be considered when planning breast-conserving therapy for nonpalpable tumors.