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 11 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 on review of their pathology slides, and received 260 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 5 1 mm, or close (carcinoma c 1 mm from the inked margin but not at the margin); or positive (carcinoma at the inked margin). A focally positive margin was defined as invasive or in situ ductal carcinoma at the margin in three or fewer low-power fields. The first site of recurrent disease was classified as either ipsilateral breast recurrence (IBR) or distant metastasis/regional lymph node failure.