Recurrence rates and analysis of close or positive margins in patients treated without re-excision before radiation for breast cancer

Purpose: This study examines the risk of local recurrence in a group of patients accepted for radiation therapy after breast-conserving surgery despite having a close or positive resection margin. Methods and Materials: Two hundred patients with early-stage breast cancer were treated by radiation with a nonnegative margin :52 mm from January 1974 to September 2001. The median age was 61 years. Margins were positive in 29% and close (<= 2 mm) in 71%. The median dose was 64 to 66 Gy. The median follow up was 5.9 years. Results: The number of resection margins close or positive was I in 73% of patients, 2 in 14%, 3 in 1%, and unknown in 12%. The margin location was 23% anterior, 24% posterior, 12% medial, 12% lateral, 17% superior, and 12% inferior. Reasons for not reexcising were advanced age/comorbidities in 7%, anterior location under skin in 25%, posterior location to muscle in 15%, focal involvement in 13%, no extensive intraductal component in 5%, surgeon refusal in 15%, and patient refusal in 20%. There was a strong association between an anterior or posterior margin location and the rationale of no additional breast tissue at the margin to reexcise before radiation. The risk of local recurrence at 5 and 10 years was 3% and 5%, respectively. Conclusions: Further research of close and positive margins is needed to validate features identified in this series, particularly nonbreast tissue anatomic margins, that are associated with low risks of local recurrence after radiation.