Surgical excision with 2-mm clear margins combined with whole-breast irradiation may be the optimal standard to reduce recurrence in patients with ductal carcinoma in situ (DCIS), according to a multidisciplinary consensus panel.
Despite the widespread use of surgical excision in breast-conserving therapy among patients with DCIS, there is no consensus on the optimal negative margin to prevent recurrence and re-excision. Therefore, the Society of Surgical Oncology, the American Society for Radiation Oncology, and the American Society of Clinical Oncology convened a panel to answer the following question: What margin width minimizes the risk of ipsilateral breast tumor recurrence in patients with DCIS receiving breast-conserving surgery?
The guideline panel reviewed 20 studies including 7,883 DCIS patients. A median of 100% of patients received whole-breast radiation therapy and a median of 21% received endocrine therapy. Patients were followed for a median of 6.5 years and the median incidence of recurrence was 8.3%.
“There is no debate that a positive margin ... implies a potentially incomplete resection and is associated with a higher rate of [recurrence],” according to Monica Morrow, MD, of Memorial Sloan-Kettering Cancer Center, and her fellow panelists. Further, the addition of whole-breast irradiation did not negate this increased risk, the panelists noted (J Clin Oncol. 2016 Aug. doi: 10.1200/JCO.2016.68.3573).
According to the meta-analysis, patients with 2-mm negative margins plus whole-breast irradiation were significantly less likely to experience ipsilateral breast tumor recurrence compared with patients who had excisions with positive margins.
“Margins of at least 2 mm are associated with a reduced risk of [recurrence] relative to narrower negative margin widths in patients receiving [whole-breast radiotherapy]. The routine practice of obtaining negative margin widths wider than 2 mm is not supported by the evidence,” they wrote.
The panel also noted that treatment with excision alone is associated with higher rates of recurrence compared with treatment involving with both excision and whole-breast radiation therapy. However, if patients are treated with excision alone, the optimal margin, which is unknown for this subset of patients, should be at least 2 millimeters, according to the guideline.
Due to variability in specimen sampling and in margin evaluation and assessment, “clinical judgment must be used in determining whether patients with smaller negative margin widths (0 or 1 mm) require re-excision,” the panelists noted. “The findings should not be extrapolated to DCIS patients treated with [accelerated partial breast irradiation] or those with invasive carcinoma for whom a separate guideline has been developed,” Dr. Morrow and her associates wrote.
The guideline development process was funded by the Susan G. Komen Foundation. The authors had no relevant disclosures to report.
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