Impact of axillary lymph node dissection (ALND) on survival in patients with ypN1 breast cancer that receive regional nodal irradiation (RNI): A national cancer database (NCDB) analysis.

Abstract

572 Background: The innovation of sentinel lymph node biopsy (SLNB) has allowed many patients with invasive breast cancer to forego ALND. However, the benefit of ALND is unclear in patients with pathologic N1 disease detected on SLNB following neoadjuvant chemotherapy, particularly in patients who receive adjuvant regional nodal irradiation. Methods: The National Cancer Database (NCDB) was queried for women ages 18-75 with cT1-3N1, and ypT0-T3N1M0 invasive breast cancer who underwent definitive surgical resection with axillary staging and also received adjuvant RNI. Patients treated from 2012 – 2015 were included to allow for appropriate coding of extent of axillary surgery. Overall survival (OS) was estimated using the Kaplan-Meier method and compared between patients who received SLNB alone and ALND with or without SLNB utilizing log rank testing. Propensity matching was performed to reduce the impact of potential confounders and balance sample bias. Cox proportional hazards regression was used to identify predictors of overall survival. Results: A total of 1411 women were identified who met inclusion criteria. The median age was 52 (23-75) years. 206 (15%) women had SLNB alone and 1205 (85%) had ALND with or without SLNB. Five year OS was 73% in patients who underwent ALND compared to 76% in those who had SLNB alone (p =0.39). Following propensity matching by age, race, Charlson Deyo Comorbid Condition score, pT stage, grade, ER status, and HER2 status, 5 year OS was 79% in patients who underwent SLNB alone vs. 69% in patients who had ALND performed (p = 0.33). On Cox regression analysis, none of the variables predicted for 5 year OS. Conclusions: ALND in addition to RNI did not improve survival in patients with cT1-3N1M0 and ypT0-3N1M0 breast cancer compared to SLNB and RNI. We await results of the Alliance 011202 randomized trial for prospective validation of ALND omission in a similar subset of patients. [Table: see text]