Long-term oncologic outcomes of minimal access (endoscopic or Robotic Assisted) nipple-sparing mastectomy compared with conventional approach in breast cancer – a propensity score matching analysis

Objective: To compare the clinical and oncologic outcomes of minimal access (endoscopic- or robotic-assisted) nipple-sparing mastectomy (MA-NSM) and conventional NSM (C-NSM). Background: MA-NSM has been increasingly applied in the treatment of patients with breast cancer. However, high-quality long-term follow-up data remains lacking. Materials and Methods: A retrospective analysis of a prospectively collected database was conducted from single institute to compare the oncologic outcome of MA-NSM versus C-NSM. The clinical results and oncologic outcome (margin involvement rate, local recurrence and overall survival) were compared. To prevent bias, a cohort study approach was conducted with propensity score matching (PSM) method. Results: During study, 1108 NSM procedures were performed. After inclusion and exclusion criteria, 905 NSM procedures were enrolled. These included 317 MA-NSM (245 endoscopic-assisted NSM and 72 robotic-assisted NSM), and 588 C-NSM cases. After PSM, there were 289 MA-NSM and 289 C-NSM cases compared. There were fewer major (Clavien-Dindo grade II and above) complications in MA-NSM compared with C-NSM (4.1% versus 10.7%, p = 0.03). The margin involvement rate of C-NSM was 3.5% versus 3.8% for MA-NSM (p>0.99). The follow-up duration of C-NSM patients was longer at 75.3 ± 46 months compared to 66.1 ± 39.1 months for MA-NSM patients. In Kaplan–Meier survival curve analysis, there was no difference in recurrence-free survival (p = 0.17), however metastasis-free (p = 0.048), disease-free (p = 0.048) and overall survival curves (p = 0.025) showed marginally significant difference between C-NSM and MA-NSM after PSM. Conclusion: Our current study demonstrates that MA-NSM is oncologically safe, with comparable results in margin involvement, locoregional recurrence, distant metastasis and overall survival compared to C-NSM.