Are the ACOSOG Z0011 Trial Findings Being Applied to Breast Cancer Patients Undergoing Neoadjuvant Chemotherapy?

In 2010, the ACOSOG Z0011 trial showed equivalent survival and recurrence between sentinel lymph node biopsy (SLNB) alone versus axillary lymph node dissection (ALND) for those with a tumor positive sentinel node (SN). We examined national trends in axillary surgery following neoadjuvant chemotherapy (NAC) for clinically node positive disease in the years prior to and after the Z0011 trial publication. 12,063 women with cT1-4N1M0 invasive breast cancer who underwent NAC from 2006 to 2013 and had 1-3 positive nodes on pathology were selected from the National Cancer Data Base. We defined SLNB as 1-4 nodes and ALND as ≥10 nodes examined. 2,704 women (22.4%) underwent SLNB alone and 9,359 (77.6%) underwent ALND. The rate of SLNB increased from 25.6% in 2006 to 33.3% in 2012 in patients that underwent lumpectomy (p < 0.01) and increased from 20.6% to 22.8% in patients that underwent mastectomy (p = 0.25). Patients treated at Community centers (30.4% versus 19.2% at Academic centers) and those with less positive nodes (32.2% for 1 positive node versus 10.1% for 3 positive nodes, p < 0.01) were more likely to have SLNB alone compared to ALND. On multivariate analysis, treatment with lumpectomy (OR 1.46, CI 1.28-1.67), lower number of positive nodes (OR 3.98, CI 3.29-4.82) and lobular subtype (OR 1.82, CI 1.42-2.34) were independent predictors of receiving SLNB alone after NAC. Approximately 22% of patients with cN1 breast cancer underwent SLNB alone for pN1 disease after NAC. Ongoing clinical trials will determine if recurrence and survival rates are equivalent between SLNB and ALND groups.