Do the ACOSOG Z0011 Criteria Affect the Number of Sentinel Lymph Nodes Removed?

Abstract

We sought to determine if adoption of the Z0011 criteria was associated with removal of more sentinel lymph nodes (SLNs). In a retrospective review of a prospective database of breast cancer patients treated at our institution from 2006 to 2013, we identified 5213 eligible patients who elected to undergo breast-conserving surgery; 2372 were treated pre-Z0011 and 2841 post-Z0011. Clinicopathologic factors were collected, and univariate and multivariate models were fit to identify variables associated with number of SLNs removed. Median patient age, 60 years, did not differ between groups. Median tumor size was similar in both groups: 1.1 (0.05-5.0) cm in the pre-Z0011 group and 1.2 (0.1-5.2) cm in the post-Z0011 group. The mean number of SLNs excised in the pre-Z0011 patients was 2.8 compared with 2.9 in post-Z0011 patients (p = 0.01). Three or fewer lymph nodes were removed in 1771 (75 %) pre-Z0011 patients compared with 2006 (71 %) post-Z0011 patients (p = 0.01). Factors associated with the removal of more SLNs on multivariate analysis included adoption of ACOSOG Z0011 criteria (p = 0.03), young age (p ≤ 0.0001), and large tumor size (p = 0.0005). Axillary lymph node dissection (ALND) was performed in 379 (16 %) patients pre-Z0011 compared with 68 (2 %) node-positive post-Z0011 patients (p < 0.0001). Since the adoption of Z0011 criteria, we found significantly fewer patients undergoing ALND for positive SLNs. We noted a significant, slight shift in the removal of ≥4 SLNs. The Z0011 criteria were not associated with a clinically significant increase in the number of SLNs removed.