Positive margins after breast-conserving therapy: localization technique or tumor biology?

BackgroundThe relative contributions of patient and tumor factors versus radiologic localization technique to the rates of inadequate margins of excision in breast-conserving therapy have not been defined.MethodsPatients undergoing breast-conserving therapy were studied. Margins less than 2 mm from tumor were considered inadequate.ResultsOf 539 patients, 31% were guided by palpation and 69% were guided by preoperative radiologic localization. The palpation-guidance patients had larger tumors (P < .0001) and more nodal metastases (P = .0005). The rates of inadequate margins were 10% for palpation-guided patients and 11% for radiologic-localization patients (P = .53). The 3-year rates of local recurrence were .7% for palpation-guided patients and 1.8% for radiologic-guided patients (P = .5).ConclusionsPatient, tumor, and intraoperative pathologic factors, not just localization device shortcomings, produce inadequate margins of excision in breast-conserving therapy. A reasonable expected rate of inadequate margins owing to patient and tumor factors is 10%. Quality improvement for margin management must focus on intraoperative assessment of margins, especially for patients with identified risk factors, in addition to improving localization technique.