Does the volume of ductal carcinoma in situ impact the positive margin rate in patients undergoing breast conservation for invasive breast cancer?

BackgroundWe sought to investigate whether the volume of ductal carcinoma in situ (DCIS) impacts margin status in patients undergoing lumpectomy for invasive breast cancer.MethodsWe identified 358 patients with stages I–III invasive breast cancer and associated DCIS who were treated with breast-conserving therapy from 1999 to 2009. Data included patient and tumor characteristics, percentage of DCIS (<25%, 26%–50%, or >50%), and pathologic outcomes. Data were compared using chi-square and Fisher exact tests. A two-tailed P value of <0.05 was considered significant.ResultsThe 358 patients had a mean age of 58 ± 13 y; 260 (72%) patients were >50 y. The volume of DCIS in lumpectomy specimens was <25% in 296 (83%) patients, 26%–50% in 29 (8%) patients, and >50% in 33 (9%) patients. Tumors with decreasing DCIS volume were more likely to be estrogen receptor positive (239 [82%] with <25% DCIS, 21 [72%] with 26%–50% DCIS, 22 [67%] with >50% DCIS; P = 0.026). DCIS volume was not significantly associated with patient age, tumor size, grade, and stage, nodal status, progesterone receptor status, or Her2 status (P > 0.05). Overall, 137 (38%) patients had one or more positive margins, including 97 of 296 (33%) with <25% DCIS volume, 17 of 29 (59%) with 26%–50% DCIS volume, and 23 of 33 (70%) with >50% DCIS volume (P < 0.0001).ConclusionsThe volume of DCIS associated with an invasive breast cancer in the final lumpectomy specimen is a strong predictor of positive surgical margins. Future analyses will focus on the ability of core pathology to provide this information for intraoperative surgical decision making.