Abstract: Incision Choices in Nipple-Sparing Mastectomy: A Comparative Analysis of Outcomes and Evolution of a Clinical Algorithm

Abstract

PURPOSE: Nipple-sparing mastectomy (NSM) allows for preservation of the entire nipple-areola complex utilizing various unique incision patterns. Reconstructive trends and overall risk associated with these diverse NSM incisions have yet to be fully established. METHODS: All NSMs from 2006 to 2017 were identified; outcomes were stratified by type of mastectomy incision: lateral or vertical radial, inframammary fold, Wise pattern, previous, and periareolar. Mastectomy incisions other than these were excluded from analysis. Descriptive statistics and measures of central tendency were used to describe absolute and mean results. ANOVA and Chi-squared analysis were used to compare groups in terms of demographics and outcomes. Full and reduced model multivariate analyses were performed to identify the independent effect of mastectomy incision type on the occurrence of any complication. p-Values <0.05 were deemed significant. RESULTS: A total of 1212 NSMs were performed with 1207 NSMs included for final analysis. Of these, 638 (52.9%) utilized an inframammary fold incision, 294 (24.4%) utilized a lateral radial incision, 161 (13.3%) used a vertical radial incision, 60 (5.0) utilized a Wise pattern incision, 35 (2.9%) used a previous incision, and 19 (1.6%) utilized a periareolar incision. Demographics for each NSM incision were heterogeneous and differed significantly with regards to age (p<0.001), body-mass index (p<0.001), smoking (p=0.001), diabetes mellitus (p<0.001), mastectomy indication (p<0.001), prior chemotherapy (p=0.006), mastectomy laterality (p<0.001), performance of a sentinel lymph node biopsy (p<0.001), pathologic cancer stage (p<0.001), reconstruction modality (p<0.001), adjuvant chemoradiation (p=0.031; p=0.002), and follow-up time (p<0.001). The groups were similar with regards to prior radiation (p=0.386) and sentinel lymph node biopsy positivity (p=0.327). A crude, unadjusted multivariate logistic regression analysis examining for the occurrence of any complication revealed a significant difference among the six cohorts of varying NSM incisions (p<0.001). Two bookend cohorts emerged with vertical radial (16.1%) and inframammary fold incisions (21.0%) having lower overall complication rates while lateral radial (31.6%), Wise pattern (50.0%), previous (45.7%), and periareolar (36.8%) experienced higher overall rates. Post-hoc adjusted z-tests were performed which identified the vertical radial and inframammary fold incision cohorts as homogeneous subgroups. Full and reduced models of the multivariate logistic regression analysis were then performed to determine adjusted outcomes. The Hosmer and Lemeshow chi-square test results were insignificant for both the full and reduced multivariate regression models (p=0.401; p=0.061), indicating good fit. In the full model, age (p=0.013) and body-mass index (p<0.001) emerged as significant risk factors for the occurrence of any complication with NSM and were included in the reduced model. In the reduced multivariate logistic regression model, inframammary fold incisions (p=0.001) emerged as a significant protective factor for overall complications after adjustment for other factors. Wise pattern incisions (p=0.051) increased the odds of complications, although not quite significantly (p=0.051). Age (p=0.007) and body-mass index (p<0.001) continued to significantly increase risk of complications in this model. CONCLUSION: NSM may be safely performed using various mastectomy incisions, each with unique advantages and limitations. Overall, inframammary fold incisions appear to be associated with lowest complications while Wise pattern incisions may increase risk.