American College of Surgeons Oncology Group (ACOSOG) Z0011: Impact on surgeon practice patterns

Introduction. The ACOSOG Z0011 trial has been described as practice-changing. The goal of this study was to determine the impact of the trial on surgeon practice patterns at our institution. Methods. This is a review of practice patterns comparing the year before release of Z0011 to the year after an institutional multidisciplinary meeting discussing the results. Patients meeting Z0011 inclusion criteria were identified. Clinicopathologic data were compared between the cohorts. Results. There were 658 patients with clinical T1-2 tumors planned for breast conservation: 335 in the pre- Z0011 cohort and 323 post-Z0011. Sixty-two (19 %) patients were sentinel lymph node (SLN) positive in the pre-Z0011 group versus 42 (13 %) post-Z0011 (p = 0.06). Before Z0011, 85 % (53/62) of SLN-positive patients underwent axillary node dissection (ALND) versus 24 % (10/42) after Z0011 (p<0.001). After Z0011, surgeons were more likely to perform ALND on patients with larger tumors (2.2 vs. 1.5 cm, p = 0.09), lobular histology (p = 0.01), fewer SLNs (1 vs. 3, p = 0.09), larger SLN metastasis size (4 vs. 2.5 mm, p = 0.19), extranodal extension present (20 vs. 6 %, p = 0.16), or a higher probability of positive non-SLNs (p = 0.03). Surgeons were less likely to perform intraoperative nodal assessment post-Z0011 (26 vs. 69 %, p<0.001) resulting in decreased median operative times for SLN-negative patients (79 vs. 92 min, p<0.001). Conclusions. Surgeons at our institution have implemented Z0011 results for the majority of patients; however, clinicopathologic factors still impact the decision to perform ALND. Z0011 results have significantly impacted practice by decreasing rates of ALND, use of intraoperative nodal evaluation, and operative times.