Is extracapsular nodal extension in sentinel nodes a predictor for nonsentinel metastasis and is there an impact on survival parameters?-A retrospective single center cohort study with 324 patients.

The Z0011 trial has fundamentally changed axillary management in breast cancer patients. However, some important questions remain, like the role of extracapsular nodal extension (ENE) in positive sentinel nodes and the need for further axillary treatment. In this retrospective cohort study, we reviewed and analyzed data from 342 clinically node negative (cN0) breast cancer patients with a positive sentinel node and subsequent axillary lymph node dissection (ALND) from the BRENDA data base. The 104 (30.4%) ENE positive patients had a significantly higher proportion of ≥3 positive axillary lymph nodes (65.0%) compared to ENE negative patients with a positive sentinel node (21.4%). Likewise, ENE positive patients had significantly more often lymph node metastasis size >2 mm (96.2%) than ENE negative patients (72.7%). T1 status was observed significantly more often in ENE negative patients (53.2%) than in ENE positive patients (24.0%). While ENE was linked to worse overall survival in univariate analysis, this effect disappeared when adjusting for nodal status, age, and comorbidities in multivariate analysis. ENE of the sentinel node is an important predictor for nonsentinel lymph node involvement. We suggest that ENE influences survival only via a higher number of positive nodes - one of the most predictive parameters for survival outcome in breast cancer.