Predicting the status of the nonsentinel axillary nodes a - Multicenter study

Background: Sentinel lymph node (SLN) biopsy is a minimally invasive proced ure that provides accurate nodal staging, information. The need for complet ion axillary dissection after finding a positive SLN for breast cancer has been questioned. Hypothesis: The presence of nonsentinel node (NSN) metastases in the axilla ry dissection specimen correlates with tumor size, the number of SLNs remov ed, and the number of positive SLNs. Design: Prospective, multi-institutional study. Participants and Methods: The University of Louisville Breast Cancer Sentin el Lymph Node Study is a nationwide study involving 148 surgeons. All patie nts underwent SLN biopsy, followed by level I/II axillary dissection. All S LNs were evaluated histologically at a minimum of 2-mm intervals. Immunohis tochemical analysis using antibodies for cytokeratin was performed at the d iscretion of each participating institution. All NSNs were evaluated by rou tine histologic examination. Results: An SLN was identified in 1268 (90%) of 1415 patients. Increasing t umor size was significantly correlated with increasing likelihood of positi ve NSNs: Tla, 14%; Tlb, 22%; Tlc, 30%; T2, 45% and T3, 57%;, (P=.002, X-2 t est). The presence of positive NSNs was not significantly associated with t he number of SLNs removed. Patients with more than 1 positive SLN were more likely to have positive NSNs than those with only 1 positive SLN (50% vs 3 2%; P<.001, X-2 test). Increasing tumor size and the presence of multiple p ositive SLNs were also associated with the presence 3 or more positive axil lary nodes. Multivariate analysis confirmed that turner size and thr number of positive SLNs were independent factors predicting the presence of posit ive NSNs. Conclusion: The likelihood of positive NSNs correlates with increasing tumo r size and the presence of multiple positive SLNs. However, even patients w ith small primary tumors have a substantial risk of residual axillar) nodal disease after SLN biopsy. These data will be helpful in counseling patient s regarding the need for completion axillary dissection after a positive SL N is identified.