Two or more metastatic sites were found at autopsy in 84% of cases. The most common metastatic sites are lungs, followed by the intrathoracic and neck lymph nodes.

We present a novel, international, multicenter, predictive tool to assess the risk of additional axillary metastases after tumor-positive sentinel node biopsy in breast cancer. The predictive model performed well in internal and external validation but needs to be further studied in each center before application to clinical use.