Nipple-Sparing Mastectomy and Adequate Margins for Patients With Ductal Carcinoma In Situ.

Abstract

For patients with ductal carcinoma in situ (DCIS) undergoing breast conservation surgery (BCS), guidelines advise a margin width of at least 2mm, with studies demonstrating decreased recurrence risk compared to narrower margins. However, limited data exist establishing if this margin is appropriate in mastectomies, and specifically for nipple-sparing mastectomy (NSM). Consequently, we evaluated the margins of DCIS patients undergoing NSM and resulting oncologic outcomes. A single-institution retrospective review was performed in patients with DCIS or DCIS with microinvasion (DCIS + MI) undergoing NSM from April 2010 to December 2021. Patient and tumor characteristics, margin status, treatment, and outcomes information were collected. The association between margins and local-regional (LRR) and distant recurrence (DR) were examined. 161 patients were included, comprising 284 NSM (164 therapeutic, 120 prophylactic). 153 patients had DCIS and 8 had DCIS + MI. Most patients had hormone sensitive, 123 (76.4%), and nuclear grade 2, 72 (44.7%), disease. In total, 35 (21.7%) patients had positive or <2mm margins. Of these, 21 (60%) involved the anterior margin. At a median follow-up of 45 months (range 0-151), 2.5% (n = 4) had a LRR and .6% (n = 1) had a DR. Of patients with a recurrence, only 2 had positive or <2mm margins, 1 had received endocrine therapy, and none received adjuvant radiation. No specific margin status was found to correlate with recurrence for patients with DCIS or DCIS + MI undergoing NSM, with an altogether low recurrence risk. Overall, this suggests that recommended DCIS margins in BCS doesn't necessarily apply in NSM, where margins of <2mm may be acceptable.