Low rates of ipsilateral breast tumor recurrence (IBTR) was observed with the use of a 2-mm margin as the standard for an adequate margin in ductal carcinoma in situ (DCIS) treated with whole-breast irradiation (WBRT), and this standard has the potential to decrease re-excision rates, improve cosmetic outcome, and decrease health care costs. This according to a consensus guideline from the Society of Surgical Oncology, the American Society for Radiation Oncology, and the American Society of Clinical Oncology developed from a systematic review of 20 studies including 7,883 patients. Among the key guideline findings:
- Negative margins halve the risk of IBTR compared with positive margins defined as ink on DCIS.
- A 2-mm margin minimizes the risk of IBTR compared with smaller negative margins.
- More widely clear margins do not significantly decrease IBTR compared with 2-mm margins.
- Negative margins <2-mm alone are not an indication for mastectomy.
The authors concluded that clinical judgment should be used in determining the need for further surgery in patients with negative margins <2 mm.
Morrow M, Van Zee KJ, Solin LJ, et al. Society of Surgical Oncology—American Society for Radiation Oncology—American Society of Clinical Oncology consensus guideline on margins for breast-conserving surgery with whole-breast irradiation in ductal carcinoma in situ. [Published online ahead of print August 15, 2016]. J Clin Oncol. doi:10.1200/JCO.2016.68.3573.