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Predicting the status of the nonsentinel axillary nodes: a multicenter study
S L Wong1, M J Edwards, C Chao
1J. Graham Brown Cancer Center, University of Louisville, 529 S Jackson St, Louisville, KY 40202, USA.
Background:
Sentinel lymph node (SLN) biopsy is a minimally invasive procedure that provides accurate nodal staging information. The need for completion axillary dissection after finding a positive SLN for breast cancer has been questioned.
Hypothesis:
The presence of nonsentinel node (NSN) metastases in the axillary dissection specimen correlates with tumor size, the number of SLNs removed, and the number of positive SLNs.
Design:
Prospective, multi-institutional study.
Participants And Methods:
The University of Louisville Breast Cancer Sentinel Lymph Node Study is a nationwide study involving 148 surgeons. All patients underwent SLN biopsy, followed by level I/II axillary dissection. All SLNs were evaluated histologically at a minimum of 2-mm intervals. Immunohistochemical analysis using antibodies for cytokeratin was performed at the discretion of each participating institution. All NSNs were evaluated by routine histologic examination.
Results:
An SLN was identified in 1268 (90%) of 1415 patients. Increasing tumor size was significantly correlated with increasing likelihood of positive NSNs: T1a, 14%; T1b, 22%; T1c, 30%; T2, 45%; and T3, 57% (P =.002, chi(2) test). The presence of positive NSNs was not significantly associated with the 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 32%; P<.001, chi(2) test). Increasing tumor size and the presence of multiple positive SLNs were also associated with the presence 4 or more positive axillary nodes. Multivariate analysis confirmed that tumor size and the number of positive SLNs were independent factors predicting the presence of positive NSNs.
Conclusions:
The likelihood of positive NSNs correlates with increasing tumor size and the presence of multiple positive SLNs. However, even patients with small primary tumors have a substantial risk of residual axillary nodal disease after SLN biopsy. These data will be helpful in counseling patients regarding the need for completion axillary dissection after a positive SLN is identified.