Axillary lymph node dissection (ALND) in breast cancer patients with positive sentinel nodes is under debate. We aimed to establish two models to predict non-sentinel node (NSN) metastases in patients with micrometastases or isolated tumor cells (ITC) in sentinel nodes, to guide the decision for ALND. A total of 1,577 breast cancer patients with micrometastases and 304 with ITC in sentinel nodes, treated by sentinel lymph node dissection and ALND in [2002][2003][2004][2005][2006][2007][2008] were identified in the Danish Breast Cancer Cooperative Group database. Risk of NSN metastases was calculated according to clinicopathological variables in a logistic regression analysis. We identified tumor size, proportion of positive sentinel nodes, lymphovascular invasion, hormone receptor status and location of tumor in upper lateral quadrant of the breast as risk factors for NSN metastases in patients with micrometastases. A model based on these risk factors identified 5% of patients with a risk of NSN metastases on nearly 40%. The model was however unable to identify a subgroup of patients with a very low risk of NSN metastases. Among patients with ITC, we identified tumor size, age and proportion of positive sentinel nodes as risk factors. A model based on these risk factors identified 32% of patients with risk of NSN metastases on only 2%. Omission of ALND would be acceptable in this group of patients. In contrast, ALND may still be beneficial in the subgroup of patients with micrometastases and a high risk of NSN metastases.Axillary nodal status is the most important prognostic factor in breast cancer. Axillary lymph node dissection (ALND) has previously been standard procedure for staging of the axilla, but ALND is associated with considerable arm morbidity 1,2 and is redundant for women without lymph node metastases. Sentinel lymph node dissection (SLND) causes limited arm morbidity compared to ALND 3,2 and has, therefore, gradually replaced ALND as standard procedure for staging of the axilla. SLND allows more extensive histopathological examinations of the lymph nodes and as a result more metastases, especially more micrometastases and isolated tumor cells (ITC), are found. 4,5 Micrometastases are in Denmark defined as metastases measuring between 0.2 and 2 mm or between 10 and 100 tumor cells and ITC are defined as single cells or cell clusters <0.2 mm or <10 cells. 6 Sentinel node positive patients have generally been recommended additional ALND even if only micrometastases or ITC are found in the sentinel node. However, metaanalyses have shown that only about 20% of patients with micrometastases 7 and 12% of patients with ITC 8 in the sentinel node have metastatic spread to non-sentinel node (NSN) and the benefit from ALND in these patients is now under debate. 9,10 A recent randomized trial from the American College of Surgeons Oncology Group (Z0011) could not show any difference in axillary recurrence and survival between sentinel node positive patients with or without ALND.10 However, the study was closed...