Positive Nipple Margins and Oncologic Outcomes of Nipple-Sparing Mastectomy in a Large Community-Based Hospital System.

The American Society of Breast Surgeons recommends sending separate nipple margins (NMs) when performing nipple-sparing mastectomies (NSMs). However, the definition of a positive NM is vague. We evaluated NM management and outcomes in breast cancer patients undergoing NSM from 2010 to 2021 at our community-based hospital system through a retrospective review and descriptive analysis. A total of 619 patients (1086 NSM) were included. Median invasive tumor size was 1.5cm and median follow-up 30 months. Fourteen therapeutic NSMs had tumor within the NMs. Nine were positive using the definition "any tumor within the separate NM," and nipple-areolar complex (NAC) excised. Two were negative when positive was defined as "any tumor on ink," and were observed without recurrence. Our results suggest positive NMs warranting NAC excision could be interpreted as "any tumor on ink" and NSMs can be safely performed with low rates of positive NMs and recurrences in high-volume hospitals.