Outcomes in breast cancer patients relative to margin status after treatment with breast-conserving surgery and radiation therapy: the University of Pennsylvania experience.

PURPOSE: To evaluate the significance of final microscopic resection margin status on treatment outcomes in women with early breast cancer who are treated with breast-conserving surgery and definitive breast irradiation. METHODS AND MATERIALS: An analysis was performed of 1021 consecutive women with clinical Stage I or II invasive carcinoma of the breast treated with breast-conserving surgery and definitive breast irradiation. Complete gross excision of tumor was performed in all cases, and an axillary staging procedure was performed to determine pathologic axillary lymph node status. The 1021 patients were divided into four groups based on the final microscopic margin from the tumor excision or from the re-excision if performed. These four groups were: (a) 518 patients with negative margins; (b) 124 patients with focally positive margins; (c) 96 patients with focally close margins (< or = 2 mm); and (d) 283 patients with unknown margins.
RESULTS: Local failure was not significantly different in patients with negative, focally positive, focally close or unknown final pathologic margins of resection at 8 years (8% vs. 10% vs. 17% vs. 16%, respectively, p = 0.21). The 8-year outcome also was not different among the four groups for overall survival (86% vs. 83% vs. 88% vs. 81%, respectively, p = 0.13), cause-specific survival (89% vs. 86% vs. 88% vs. 83%, respectively, p = 0.14), no evidence of disease survival (81% vs. 73% vs. 86% vs. 77%, respectively, p = 0.09), and freedom from distant metastases (85% vs. 75% vs. 86% vs. 79%, respectively, p = 0.08).
CONCLUSION: These results demonstrate that selected patients with focally positive or focally close microscopic resection margins can be treated with breast-conserving surgery and definitive breast irradiation with 8-year local control rates and survival rates that are similar to those seen in breast-conservation patients with negative or unknown final resection margins.