Clinical impact of the Z0011 trial on axillary surgical management in Australia and New Zealand from the BreastSurgANZ Quality Audit

Background: The clinical management of the axilla in early breast cancer has changed since the Z0011 trial, which showed that axillary lymph node dissection (ALND) is not necessary in select patients with a positive sentinel lymph node biopsy (SLNB). Studies have shown a significant decrease in the rates of completion ALND (cALND) since Z0011. The aims of this study were to investigate the effect of the Z0011 trial on the management of positive axillary sentinel nodes and the trends in axillary surgical management since 2005 in Australia and New Zealand. Methods: This study utilized prospectively maintained data from the BreastSurgANZ Quality Audit (BQA). Patients with early breast cancer between 2005 and 2023 satisfying the Z0011 trial inclusion criteria undergoing SLNB or SLNB followed by cALND were identified. Results: There were 91 196 patients who underwent breast-conserving surgery and SLNB of which 12 035 were node positive therefore satisfying the Z0011 trial inclusion criteria, of which 8194 (68.1%) received SLNB only with no cALND. There has been a 55.4% reduction in the rate of cALND after 2010 when the Z0011 trial was published (P < 0.001). There was a significant downward trend in the number of cALND performed per year (R² = 0.890, P < 0.001). Conclusion: The Z0011 trial was a practice changing trial and since its publication in 2010 has been correlated with de-escalation in surgical management of the axilla and decline in the rates of cALND in Australia and New Zealand.