Pathologic margin involvement and the risk of recurrence in patients treated with breast‐conserving therapy

BACKGROUND: The relationship between the microscopic margins of resection and ipsilateral breast recurrence (IBR) after breast-conserving therapy for carcinomas with or without an extensive intraductal component (EIC) has not been adequately defined. METHODS: Of 1,790 women with unilateral clinical Stage I or II breast carcinoma treated with radiation therapy as part of breast-conserving therapy, 343 had invasive ductal histology evaluable for an extensive intraductal component (EIC), had inked margins that were evaluable for an review of their pathology slides, and received > or = 60 Gray to the tumor bed; these 343 women constitute the study population. The median follow-up was 109 months. All available slides were reviewed by one of the study pathologists. Final inked margins of excision were classified as negative > 1 mm (no invasive or in situ ductal carcinoma within 1 mm of the inked margin); negative-1 mm, or close carcinoma 1 mm margins. For patients with close margins, the rates were 2% and 0% for EIC-negative and EIC-positive tumors, respectively; the corresponding rates for patients with negative margins > 1 mm were 1% and 14%. The 5-year rate of IBR for patients with focally positive margins was 9% (9% for EIC-negative and 7% for EIC-positive patients). The 5-year crude rate of IBR for patients with greater than focally positive margins was 28% (19% for EIC-negative and 42% for EIC-positive patients). CONCLUSIONS: Patients with negative margins of excision have a low rate of recurrence in the treated breast, whether the margin is > 1 mm or < or = 1 mm and whether the carcinoma is EIC-negative or EIC-positive. Among patients with positive margins, those with focally positive margins have a considerably lower risk of local recurrence than those with more than focally positive margins, and could be considered for breast-conserving therapy.