Clinicopathologic features associated with having four or more metastatic axillary nodes in breast cancer patients with a positive sentinel lymph node.

BACKGROUND: The survival benefit of a completion axillary lymph node dissection (ALND) in patients after removal of a metastatic sentinel lymph node (SLN) is uncertain and is under study in ongoing clinical trials. The completion ALND remains necessary, however, for the identification of cases with at least four metastatic lymph nodes, in which extended-field locoregional and/or postmastectomy radiation will be recommended. Our goal was evaluate clinicopathologic features that might serve as surrogates for determining which patients with a positive SLN are likely or unlikely to belong to this high-risk subset.
METHODS: Records were reviewed for 285 patients from 2 comprehensive cancer centers who underwent completion ALND after resection of a metastatic SLN from 1995 to 2002. Clinicopathologic features were analyzed by univariate and multivariate logistic regression. Forty-one cases (14%) were found to have at least four positive nodes after ALND.
RESULTS: Fisher's exact test revealed the following features to be significantly (P < .05) associated with having four or more nodal metastases: tumor size >2 cm, lymphovascular invasion, an increasing ratio of positive SLNs to the total number of resected SLNs, extranodal extension, and the size of the SLN metastasis. Patients whose largest SLN metastasis was <2 mm had only a 1.4% risk of having four or more metastatic nodes (P < .0001).
CONCLUSIONS: We conclude that patients with SLN micrometastases face an extremely low likelihood of having extensive nodal disease on completion ALND. Patients with larger primary tumors, lymphovascular invasion, and extranodal extension are more likely to have ALND findings that will affect their cancer management.