Impact of the American College of Surgeons Oncology Group Z0011 criteria applied to a contemporary patient population

Background: The American College of Surgeons Oncology Group (ACOSOG) Z0011 trial concluded that axillary lymph node dissection (ALND) may not be necessary for all patients with sentinel lymph node (SLN) metastasis undergoing breast-conserving therapy (BCT). The aim of this study was to assess applicability of Z0011 results to our patient population and determine what percentage may be affected by these results. Study Design: Patients with clinical T1-2, N0 breast cancer, treated with surgery first between 1994 and 2009, who had 1 to 2 positive SLNs, were included in this study. Kaplan-Meier survival curves were calculated and log-rank used to compare overall survival (OS) and disease-free survival (DFS) for ALND vs SLN dissection (SLND) alone in 2 patient populations: patients undergoing BCT or total mastectomy (TM) and patients undergoing BCT only. Results: Of 861 patients, 188 (21.8%) underwent SLND alone. Of 488 (56.7%) patients who underwent BCT, 125 (25.6%) had SLND alone. Of 412 patients undergoing TM, 67 (16.3%) had SLND alone. Patients undergoing ALND were significantly younger, had larger tumors, macrometastasis, and extranodal extension in both populations. Compared with the Z0011 cohort, our BCT patients had more T1 tumors (76.0% vs 69.3%, p = 0.01) and more grade II to III tumors (87.3% vs 76.2%, p < 0.0001). After adjusting for T-stage, there were no significant differences in DFS and OS between patients undergoing SLND alone or ALND in both populations. Conclusions: Examination of our breast cancer patients with Z0011 trial criteria suggests that almost 75% of SLN-positive patients would be candidates to avoid ALND if they undergo BCT.