Safe negative-margin width in breast-conservative therapy: Results from a population with a high percentage of negative prognostic factors.

Abstract

75 Background: There remains a controversy in literature regarding adequate width of negative surgical margins in breast conservative therapy (BCT). Majority of patients included in studies on outcomes of BCT had favorable prognostic factors. Pakistani population is known to have an elevated expression of unfavorable prognostic factors. This study was done to determine safe negative margin width in a patient population with significantly higher percentage of unfavorable prognostic factors undergoing BCT. Methods: A review of patients who received BCT from 1997-2009 at Shukat Khanum Cancer Hospital was performed. A total of 603 patients whose margin status could be assessed were included. Patients were divided into close ( ≤ 2mm), free (> 2-10mm), and wide (> 10mm) margin groups. Patient characteristics, medical treatment modalities, and number of locoregional recurrences were observed for each margin group. Chi square and Fisher’s exact test were used for categorical variables. Five year locoregional control was determined for margin groups. Univariate and multivariate Cox regression analysis was performed to determine independent predictors of locoregional recurrence. Results: Out of total, 415 (69%) patients were <50 years of age. There were 82 (15%) T3/T4, 337 (56%) poorly differentiated and 238 (39%) ER/PR–ve tumors. Nodal positivity was present in 314 (52%) patients. A higher percentage of T3/T4 tumors in close margin group (25% versus 13% and 7%) (p < 0.0001) was observed. Use of neoadjuvant chemotherapy was significantly higher in close margin group (33% versus 29% and 16%) (p < 0.0001). The actual number of observed locoregional recurrences was 16 (12%), 8 (3%), and 10 (4.6%) in close, free, and wide margin groups (p = 0.002) while the expected 5 year locoregional control was 90%, 97%, and 96% (p = 0.002) respectively. On multivariate analysis tumor size stage, nodal involvement and negative margin width were independent predictors of locoregional failure. Conclusions: A negative margin width of 2mm might represent an adequate negative margin width in populations with a higher percentage of unfavorable prognostic factors.