Axillary lymph node dissection has been the standard of care after identification of a positive sentinel lymph node for breast cancer patients.
To determine the likelihood of non-sentinel lymph node involvement for patients with negative sentinel node by frozen section, who are subsequently found to have tumor cells in the sentinel node by permanent section levels and/or cytokeratin immunohistochemistry.
One hundred three patients with invasive breast cancer exhibiting negative frozen section evaluation of their sentinel node, but later found to have isolated tumor cells (n  =  46), micrometastasis (n  =  46), or metastases (n  =  11) in their sentinel node by permanent sections or immunohistochemistry, were enrolled in this prospective cohort study and underwent completion axillary dissection.
Six of 46 patients (13%) with isolated tumor cells in their sentinel node, 15 of 46 patients (33%) with micrometastasis in their sentinel node, and 2 of 11 patients (18%) with metastasis in their sentinel node had additional findings in the nonsentinel nodes. These findings resulted in a pathologic stage change in 2 patients. Predictors of positive nonsentinel nodes were 2 or more positive sentinel nodes (P  =  .002), sentinel nodes with micrometastasis versus isolated tumor cells (P  =  .03), and those with angiolymphatic invasion (P  =  .04).
Our findings lend support to axillary node dissection for patients with micrometastasis or metastasis in their sentinel nodes. However, studies with clinical follow-up are needed to determine whether axillary node dissection is necessary for patients with isolated tumor cells in sentinel nodes.