The Impact of a Focally Positive Resection Margin on the Local Control in Patients Treated with Breast-conserving Therapy

Objective: The aim of the study was to investigate the parameters affecting positive margin and the impact of positive margin on outcomes after breast-conserving therapy in patients with breast cancer. Methods: Characteristics and survival of 705 patients attempted breast-conserving therapy between January 1994 and December 2004 were retrospectively analyzed using chi(2) tests, the Kaplan-Meier methods and multivariate analyses. Results: Ninety-five (13.5%) showed positive margins at initial resection. Among them, 28 (4.0%) had negative margin on the initial frozen section; however, they finally turned out a focally positive margin with intraductal carcinoma on the permanent pathology. Positive margin at initial resection was significantly associated with lobular histology (P = 0.001), four or more involved lymph nodes (P = 0.015) and the presence of extensive intraductal component (P < 0.001). A focally positive margin did not influence local (P = 0.250; 95% confidence interval, 0.612-6.592) or regional failure (P = 0.756; 95% confidence interval, 0.297-5.311). Patients with a focally positive margin showed an advanced nodal stage and received a higher dose of irradiation and more systemic therapy. Nodal involvements were the most significant factor for locoregional failure. Conclusions: Although the achievement of negative margins is the best way to reduce local failure, patients with a focally positive margin and favorable risk factors such as node negativity and older age could have an option of close follow-up with adequate boost irradiation and adjuvant therapy instead of conversion to total mastectomy.