Predictors of nonsentinel node metastasis in patients with breast cancer after sentinel node metastasis.

HYPOTHESIS The presence of nonsentinel lymph node (NSLN) metastasis after having a positive sentinel lymph node dissection finding is associated with tumor size and stage, the presence of lymphovascular invasion, micrometastasis, and extranodal extension. DESIGN Retrospective case series. SETTING University hospital. PATIENTS Four hundred seven consecutive patients at a single institution who underwent sentinel lymph node dissection as part of breast conservation or mastectomy with biopsy-proved cancer. INTERVENTION Completion axillary lymph node dissection and definitive therapy. MAIN OUTCOME MEASURES Sentinel node metastasis, NSLN metastasis, tumor size and stage, lymphovacular invasion, micrometastasis, extronodal extension, histological tumor characteristics, and number of sentinel nodes removed. RESULTS In a univariate analysis, size of the primary tumor and extranodal extension were associated with having positive NSLN findings. The presence of micrometastasis was associated with negative NSLN findings. When all factors were included in a logistic regression analysis, the significant predictor of NSLN metastasis was extranodal extension (P =.002). Lymphovascular invasion was not associated with positive NSLN findings (P =.11). The number of sentinel nodes removed also had no bearing on the status of the NSLNs (P =.37). CONCLUSIONS Although primary tumor size and micrometastases correlate with the status of the NSLNs, extranodal extension is the most important independent predictor of NSLN metastasis. These findings may ultimately spare patients a full axillary lymph node dissection. However, pending results of larger clinical trials, full axillary lymph node dissection is still recommended for patients with sentinel lymph node metastases.