Comparison of terminal duct lobular units in the nipple areolar complex by tumor subtypes-the implication for nipple sparing mastectomy.

Abstract

e12082 Background: Nipple-sparing mastectomy (NSM) has gained popularity for surgical treatment of breast cancer. Terminal duct lobular units (TDLU) have been shown to be present in 25% of nipple areolar complex (NAC). Pathologic tumor subtype influence on presence of TDLU in the NAC has not been assessed. In addition, criteria for technically performing the dissection below the NAC have not been established. We sought to evaluate TDLU characteristics by tumor subtype and determine NSM dissection criteria below the NAC. Methods: A retrospective review was performed of 120 total and skin sparing mastectomies, 30 of each breast cancer subtype, from 1/2013 to 1/2015. The NAC of each mastectomy was assessed for number of TDLU and distance from TDLU to the skin. Results: Thirty of the 120 mastectomies (25%) had TDLU present below the NAC. Of the 30 with TDLU, there was no statistically significant difference in number of TDLU present based on tumor grade (gd) (gd 1 vs 2, p = .67; gd 1 vs 3, p = .24). Compared to luminal A, luminal B showed statistical significance (p < .05) for number of TDLU at the NAC whereas Her 2 and triple negative breast cancer (TNBC) were not statistically significant (p = .09 and .10). In mastectomies with TDLU present, gd 2 (p < .05) and gd 3 (p = .05) had a closer skin distance than gd 1. When compared by tumor subtype, there was no difference in TDLU to skin distance (table). Conclusions: NSM has been adopted as a safe oncologic approach to breast cancer treatment. Although presence of TDLU in luminal B subtype was statistically significant, this may not be clinically significant, as there were only 2 of 30 cases with TDLU. Our study indicates that a careful dissection at the level of the dermis below the NAC is necessary, as 25% of women will have TDLU present. This will provide an appropriate oncologic outcome similar to total and skin sparing mastectomy. Tumor subtype does not appear to be exclusion criteria for NSM. However, more aggressive dissection may be necessary to clear all TDLU from below the NAC in higher gd cancers. [Table: see text]