Background: Sentinel lymph node biopsy (SLNB) is now the standard of care used in the staging of the regional lymph nodes in breast cancer. As result of the wide adoption of SLNB attention turned into a detailed examination of the biopsied lymph node(s) and subsequent rise in the incidence of finding lymph node micrometastases. Micrometastases(pN1mi) is defined as a metastatic disease in the lymph node that is less than 2.0 mm but larger than 0.2mm. Isolated tumor cells (ITC) is defined as a metastatic disease in the lymph node that is smaller or equal to 0.2mm. With the rise of incidence of axillary micrometastases, there is a considerable debate on the prognostic significance and appropriate treatment recommendations for such patients.
The standard of care for evaluating the axilla in breast cancer is sentinel lymph node biopsy. For patients who happen to have positive lymph node involvement by sentinel lymph node biopsy, additional treatment of the axilla is necessary. Proceeding with total axillary lymph node dissection (ALND)while effective is associated with significant morbidity and may not be needed in all patients with positive sentinel lymph node biopsy. The AMAROS trial came to provide a needed answer, ” Can axillary radiation therapy to the axilla in a specific subset of patients with positive sentinel lymph node be done in place of ALND?”