The controversy regarding margin width in breast cancer: enough is enough.

In contemporary practice, there is no debate that appropriately selected patients with early stage invasive breast cancer can be managed with breast-conserving therapy (BCT) to include a segmental mastectomy with a negative margin followed by radiation. This is supported by multiple randomized trials demonstrating equivalent survival after BCT or mastectomy published over two decades ago. Since the publication of these trials showing the efficacy of BCT, the definition of a negative margin has been the subject of frequent debate. One of these trials, the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-06 trial, defined a negative margin as ‘‘no ink on tumor.’’ Other trials required complete resection of the tumor but did not specify a required margin width or did not evaluate microscopic margins. Therefore, despite the acceptance of BCT as the preferred approach for management of patients with early stage breast cancer, the optimal margin width required on a segmental resection has been open to interpretation. This has resulted in substantial variability in treatment often leading to recommendations for reexcision for ‘‘wider’’ negative margins. After all, everyone knows that more is better, right? In the current issue of Annals of Surgical Oncology, Moran et al. provide a consensus guideline on margins developed by the Society of Surgical Oncology (SSO) and the American Society for Radiation Oncology (ASTRO). This guideline, based on results of a systematic review of 33 studies, suggests that ‘‘no ink on tumor’’ be the standard for an adequate margin in patients with invasive cancer undergoing breast conserving surgery. In order for this ‘‘less is better’’ concept to be implemented into practice on Monday morning, it is helpful to review the goals of BCT and to understand how contemporary practice involves many different multidisciplinary considerations. The goals of BCT are to remove the primary tumor, minimize the risk of local recurrence, and achieve optimal cosmesis. Clearly margin width factors into the equation and surgeons understand the need to remove the tumor with a negative margin. This is drilled into us early in our training, and the first question that we are often asked after surgery is, ‘‘Did you get it all?’’ When excising the primary tumor, one must consider the tumor to breast size ratio and include enough normal breast parenchyma around the tumor such that a negative margin will be achieved without removing more volume of normal breast tissue than necessary. This can present a challenge in that tumors often form unusual shapes and have extensions of invasive or in situ carcinoma that go beyond the obvious palpable or radiographically evident lesion. The reality is that when we remove the tumor, this is done with an estimation of margins grossly and we cannot precisely determine the margin width (1, 2 mm, etc.) until the pathologist performs microscopic assessment. If margin assessment is performed intraoperatively with specimen imaging and immediate pathologic analysis, reexcision of any margins thought to be close or positive can be performed at the time of the initial operation without the need for a return to the operating room at a later date. This approach requires close coordination between surgery, pathology, and diagnostic radiology and may not be possible to implement in all practice settings. More often, margin assessment is determined by the final pathologic evaluation performed in the days after surgery. The surgeon plays a significant role in this evaluation because careful orientation of the specimen will prevent inking of areas that are not true margins or tracking Society of Surgical Oncology 2014