All patients with histologically confirmed invasive breast cancer and a negative axillary US who are candidates for omitting SLN biopsy or any axillary surgery will be informed about the possible participation in the study. The inclusion and exclusion criteria are verified by the investigator and written informed consent is obtained from the patient. Surgical treatment, pathological assessment and postoperative locoregional and systemic therapy should be conducted according to institutional and national standards. Since the OXYGENATE study in a non-interventional trial, the study sites do not deviate from their own institutional protocol at any timepoint. The follow up on patient status is conducted yearly during the first 5 years after surgery.
