The significance of margin status in patients with DCIS undergoing breast-conserving surgery.

Abstract

98 Background: Recently, SSO/ASTRO published a consensus statement on margins for stage I and II invasive breast cancer treated with breast conserving surgery (BCS). We examined patients with ductal carcinoma in situ (DCIS) who underwent BCS to determine the effect of clinicopathologic and treatment factors including margin status, on locoregional recurrence (LRR), breast cancer-specific (BCSS) and overall survival (OS). Methods: From 2003-2010, we conducted a retrospective chart review of 253 consecutively diagnosed patients who underwent BCS for DCIS. Clincopathologic and treatment data were extracted. Margin status was defined by pathology reports with a negative margin as ≥ 2mm, close margin < 2mm and positive margin as tumor on ink. Clinicopathologic variables were tested using the Fisher’s exact test, Chi-square test, ANOVA F-test, and Kruskal-Wallis test. A Cox proportional - Hazards model was used to calculate the impact of these factors on LRR, BCSS and OS. Results: The median age of the cohort was 57 (range 21-89) and the majority were white (79%), ER+ (78%) and underwent radiation therapy (67%). Forty six percent took anti-endocrine therapy. Of 252 patients, 29% had close margins, 63% had negative margins and 7% had unknown margins. One patient had a positive margin and was alive without disease at last follow-up. At a median follow-up of 5 years, OS was 96%. Thirteen patients experienced a LRR with a median time to recurrence of 4.9 years (5 with close margins, 7 with negative, 1 unknown). On multivariate analysis, age and PR status were significant predictors of LRR. Patients with age >70 were more likely to recur than those age 50-69 (HR 6.7 95% CI (1.7-25.4) p= 0.005) as were patients with PR negative tumors (HR 5.7 95% CI (1.7-19.5) p= 0.005). Those patients who did not receive radiation therapy had a worse OS than those who did (HR 4.3 95%CI (1.5-12.6) p = 0.007). No variables were significant for BCSS. Conclusions: In this cohort of patients with DCIS treated with BCS, age and PR status were the only predictors of LRR. OS was only impacted by receipt of radiotherapy. Margin status was not predictive of LRR, BCSS or OS. This data suggests that routine re-excision for close margins may not be warranted.