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 χ(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.