- ONCOLOGY Vol 25 No 10
- Volume 25
- Issue 10
What Are Safe Margins of Resection for Invasive and In Situ Breast Cancer?
The safety and efficacy of breast-conserving therapy (BCT) for women with early-stage breast cancer are well established. BCT entails wide excision of the tumor and appropriate nodal evaluation, followed by radiation therapy to the breast.
Adequate surgical margins in breast-conserving surgery are an important predictor of local recurrence (LR) rates. The definition of tumor-free margins in National Surgical Adjuvant Breast and Bowel Project (NSABP) trials requires that tumor cells do not touch ink, but subsequent retrospective single-institution studies have suggested that wider margins confer greater protection against LR. Particularly wide margins have been proposed for ductal carcinoma in situ. However, wider margin requirements lead to higher re-excision rates, with attendant economic, psychological, and cosmetic costs, and perhaps increased mastectomy rates. Juxtaposed against these concerns about optimal margin width, a meta-analysis of clinical trials has demonstrated the survival value of minimizing LR. We are therefore at a juncture where a reduction of LR may be achieved by tumor resection with wide margins, but data regarding optimal margin width are conflicting and the risk/benefit balance of tumorectomy with wide margins has not been demonstrated. A randomized trial of re-excision for close margins inserted into trials of systemic therapy could be considered but seems unlikely. Alternatively, detailed longitudinal data need to balance the value and the cost of wide margins. Until better data are available, the desirable margin width will vary depending on individual circumstances, including age, histology, and patient preference.
The safety and efficacy of breast-conserving therapy (BCT) for women with early-stage breast cancer are well established.[1,2] BCT entails wide excision of the tumor and appropriate nodal evaluation, followed by radiation therapy to the breast. There is broad agreement that successful breast conservation requires complete tumor excision, commonly described as a "tumor-free" or "negative" margin of resection, but the definition of a negative margin is controversial. Opinions range from the original National Surgical Adjuvant Breast and Bowel Project (NSABP) definition of "no ink on tumor," to a recommended width of 10 mm or more. A widely held position based on single-institution retrospective data is that a mandatory minimum distance between ink and tumor is necessary for good local control, but the margin width is debated. A commonly accepted definition of adequate margins requires a 2-mm distance between ink and tumor.