Ductal carcinoma in situ: size and resection volume predict margin status

There is strong evidence that breast conservation surgery (BCS) with negative margins for ductal carcinoma in situ (DCIS) is associated with low rates of recurrence. Our goal was to identify factors associated with positive margins in BCS for DCIS.

A retrospective database review identified 823 patients diagnosed with DCIS. The current analysis included 546 of those patients treated with BCS from 2000 to 2006 with complete data regarding tumor and lumpectomy dimensions. Variables analyzed included tumor size, lumpectomy volume, estrogen and progesterone receptor status, histologic subtype, grade, and age at diagnosis. χ analysis and t tests were used to identify factors that may predict positive margins. A multivariate regression model was developed to determine independent variables predictive of positive margin status.

A total of 33% of specimens had positive margins. Lumpectomy volume, tumor size, nuclear grade (low vs. high), and number of slides positive for DCIS were all significant for positive margin status by bivariate analysis. On multivariate analysis, tumor size (P < 0.001; odds ratio, 2.37; 95% confidence interval, 1.712, 3.296) and resection volume (P = 0.0006; odds ratio, 0.48; 95% confidence interval, 0.318, 0.729) remained significantly associated with positive margin status. Age at diagnosis, histologic subtype, tumor grade, and estrogen and progesterone status all were not associated with margin status.

Positive margins after BCS for DCIS are associated with larger lesions and a smaller volume of resection. With 33% of patients having positive margins, these data suggest that a more aggressive initial resection may avoid positive margins and thus lower the risk of recurrence or the need for additional surgery.