Ljubljana nomograms for predicting the likelihood of non-sentinel lymph node metastases in breast cancer patients with a positive sentinel lymph node

Several tools for predicting the likelihood of non-sentinel lymph node (non-SLN) involvement in SLN-positive breast cancer patients have been created so far. The aim of our study was to create and validate different nomograms for predicting the likelihood of non-SLN involvement that would be applicable in different institutions and that would also include the results of the preoperative US examination of the axilla. From January 2000 to January 2009, 534 breast cancer patients underwent axillary lymph node dissection (ALND) due to metastatic SLN at our institution. Using logistic regression results three nomograms differing in the inclusion of the results of intraoperative examination of SLN were created. The nomograms were validated using bootstrap methods. In all three nomograms, US examination of the axilla was a powerful independent variable. Other variables included (different in different nomograms) were tumor size, lymphovascular invasion, metastasis size in SLN, number of negative and number of positive SLNs. Mean absolute error and mean area under the ROC curve equals to 0.016 and 0.77 for the first, 0.023 and 0.75 for the second and 0.014 and 0.79 for the third nomogram. Three nomograms for predicting the likelihood of non-SLN metastases including the results of the preoperative US examination of the axilla were created at our institution. They differ in the inclusion of the results of intraoperative examination of SLNs and are thus applicable in different institutions. The validation results seem promising and omission of completion ALND might be considered in patients with the probability of having non-SLN metastases of 10% or less.