Residual cancer found on re-excision for close and positive margins after breast conservation for early-stage breast cancer: A single-institution review.

Abstract

55 Background: The SSO/ASTRO guidelines for margins on breast-conservation therapy (BCT) were recently published, recommending re-excision for positive margins only defined as ink on invasive cancer. The aim of our study is to retrospectively analyze our institution’s re-excision rate and the rate of finding residual cancer in the re-excision specimen when re-excisions were performed for positive and/or close margins. We want to confirm that our institution’s data for re-excision rates and residual cancer rates are comparable to national data from where the SSO/ASTRO guidelines were derived. Methods: A 3-year (2010 to 2012) retrospective review of data from our institution’s prospectively collected breast cancer database was performed for all stage 0, I, and II breast cancer patients who underwent BCT with subsequent re-excision or completion mastectomy for close or positive margins. Close margins were divided into two groups of < 1 mm or 1 to 2 mm margins, and positive margins were defined as tumor cells present on ink of specimen. Results: A total of 688 patients were analyzed. Our population was found to consist mostly of Caucasian females who were postmenopausal and married. 68% (468/688) of patients were found to have invasive ductal carcinoma (IDC), of which 27.8% (130/468) underwent re-excision for positive and/or close margins. Rates of residual cancer found in margins that are positive, < 1 mm, and 1-2 mm were 54.8% (17/31), 56% (14/25), and 6.3% (1/16) respectively. For DCIS, 38.9% (65/167) underwent re-excision. Rates of residual cancer found in margins that are positive, < 1 mm, and 1 to 2 mm were 38.9% (7/18), 28.6 % (4/14), and 20% (2/10) respectively. Conclusions: Our results reveal that in our institution, re-excision rates are comparable to published data. However, in patients with both positive and < 1 mm margins, the rates of finding residual cancer in the re-excision specimen was higher than the national average. Therefore, in our institution, further analysis is necessary prior to adopting the current recommended guidelines by SSO/ASTRO to prevent adverse impact in local recurrence rate.