Objective: The aim of this retrospective study was to identify biological features of primary breast cancer from which to predict the presence of further axillary involvement in patients bearing micrometastases in the sentinel lymph node (SLN).
Methods: From a starting group of 690 patients, we isolated patients with micrometastases in the SLN. Those patients were classified according to the presence/absence of further metastases in nonsentinel lymph nodes (NSLNs). We examined primary tumor features to identify any relevant difference. Analysis of primary tumors evaluated histology, tumor size, lymphovascular invasion, mitotic index (Mib-1), estrogen and progesterone receptor status (ER/PR status), C-erb B-2 (HER-2/neu) expression and amplification, and p53 expression. Chi square analysis for statistical significance was applied.
Results: Of the original 690 patients, 296 showed some kind of metastases in the SLN; 238 patients had gross metastases in the SLN. After axillary lymph node dissection (ALND), 102 patients (43%) had NSLNs with metastases, and 136 (57%) had negative axillary non-sentinel nodes. Another 58 patients harbored solitary micrometastases in the SLN. After ALND, 8 (14%) patients had further NSLN involvement, and 50 (86%) had negative axillary nodes.
Conclusions: Analysis of the primary breast lesion in patients with micrometastatic SLN and metastatic NSLNs revealed the presence of lymphovascular invasion, Mib-1 index > 10%, and tumor size > 2 cm. Patients without lymphovascular invasion, Mib-1 < 10% and T size < 2 cm could avoid further ALND.