The American College of Surgeons Oncology Group published results of the Z-0011 Trial in 2010.

The trial studied invasive breast cancer patients who were treated with breast conserving surgery (the removal of breast cancer and small amount of surrounding healthy tissue) and sentinel node biopsy (removal and testing of the first lymph node or nodes to which cancer cells are most likely to spread, called sentinel lymph nodes) where the sentinel lymph nodes were found to contain cancer cells.

Results showed rates of breast cancer-free survival and overall survival were the same for women who underwent further surgery to remove more nodes in the armpit (axillary clearance) compared with those who were treated with observation only.

The Z-0011 Trial results suggested that axillary clearance is not necessary for all women having breast conserving treatment where one or two sentinel lymph nodes were found to be positive for cancer cells.

In this study, the BreastSurgANZ Quality Audit database was analysed to identify the proportion of breast cancer cases where the results of the Z-0011 Trial would be directly relevant. These cases made up less than 7% of breast cancer cases diagnosed between 2005 and 2010, indicating that the impact of the trial on clinical practice in Australia and New Zealand is small.