Use of pathologic factors to assist in establishing adequacy of excision before radiotherapy in patients treated with breast-conserving therapy

Abstract

Background: We reviewed our experience in patients with early-stage breast carcinoma treated with breast-conserving therapy (BCT) to identify pathologic factors useful in defining the adequacy of excision before radiotherapy (RT).

Methods and materials: All slides from 607 consecutively treated cases of Stage I-II breast carcinoma were reviewed by one pathologist. Numerous pathologic factors were evaluated for their association with ipsilateral breast failure (IBF). Margin distance was classified as negative, near (<0.50 low-power field), or positive. The amount of carcinoma near the final margin was measured as the width of invasive carcinoma and number of ducts with carcinoma in situ near the margin and divided into three groups: near-least, near-intermediate, and near-greatest amount. The median follow-up was 8.5 years.

Results: Patients with negative, near-least, near-intermediate, and near-greatest amount of carcinoma near the margin, and positive final margins had a 12-year IBF rate of 9%, 6%, 18%, 24%, and 30%, respectively. On multivariate analysis, only the amount of carcinoma near the margin was independently associated with IBF (p <0.001). To help explain these observations, 441 initial and reexcision specimens were examined. The amount of carcinoma near the initial margin and the invasive carcinoma/specimen maximal dimension ratio were significantly associated with greater amounts of residual carcinoma in adjacent breast parenchyma.

Conclusion: The amount of carcinoma near the margin, in addition to margin status, appears to be directly related to an increased risk of IBF in patients treated with BCT. Pathologic factors that incorporate the amount of excised breast parenchyma and amount of carcinoma near the margin may be useful to clinicians in deciding whether a patient has undergone adequate excision for BCT.