Effect of Margin Status on Local Recurrence After Breast Conservation and Radiation Therapy for Ductal Carcinoma In Situ

Purpose There is no consensus on what constitutes an adequate surgical margin in patients receiving breast-conserving surgery (BCS) and postoperative radiation therapy (RT) for ductal carcinoma in situ (DCIS). Inadequate margins may result in high local recurrence, and excessively large resections may lead to poor cosmetic outcome without oncologic benefit. Methods A comprehensive search for published trials that examined outcomes after adjuvant RT after BCS for DCIS was performed using MEDLINE and cross referencing available data. Reviews of each study were conducted, and data were extracted. Primary outcome was ipsilateral breast tumor recurrence (IBTR) related to surgical margins. Results A total of 4,660 patients were identified from trials examining BCS and RT for DCIS. Patients with negative margins were significantly less likely to experience recurrence than patients with positive margins after RT (odds ratio [OR] = 0.36; 95% CI, 0.27 to 0.47). A negative margin significantly reduced the risk of IBTR when compared with a close (OR = 0.59; 95% CI, 0.42 to 0.83) or unknown margin (OR = 0.56; 95% CI, 0.36 to 0.87). When specific margin thresholds were examined, a 2-mm margin was superior to a margin less than 2 mm (OR = 0.53; 95% CI, 0.26 to 0.96); however, we saw no significant difference in the rate of IBTR with margins between 2 mm and more than 5 mm (OR = 1.51; 95% CI, 0.51 to 5.0; P > .05). Conclusion Surgical margins negative for DCIS should be obtained after BCS for DCIS. A margin threshold of 2 mm seems to be as good as a larger margin when BCS for DCIS is combined with RT.