Prediction of metastasis to non-sentinel nodes by sentinel node status and primary tumor characteristics in primary breast cancer in Taiwan

We aimed to determine how to approach the axilla after finding a positive sentinel node (SN) for a woman with breast cancer in Taiwan. We used blue dye staining to identify the SN in 824 procedures on 811 patients with breast cancer small than 3 cm by a single surgeon. All patients underwent SN biopsy, followed by at least level II axillary dissection. All SNs were evaluated histologically and immunohistochemically with anti-cytokeratin antibodies. Non-SNs were examined by routine histology. SNs were identified in 814/824 procedures (98.8%). SN metastases were found in 286/814 (35.1%). Subsequent axillary dissections revealed tumors in non-SNs in 188 (65.7%) of these patients. There was a relatively high incidence of non-SN metastases in our population. Tumor exhibiting high nuclear grading, ER-, PR-, Erb-2/neu overexpression, lymphovascular invasion, increasing tumor size, multiple positive SNs, and macrometastatic size in SNs (> 2 mm) were all significantly correlated with non-SN metastases. Multivariate analysis showed that tumor size, the number of positive SNs, and the metastatic size in SNs were independent factors predicting the presence of positive non-SNs. Small (<2 cm) cancers, having only micrometastatic foci in the SN and having only one SN involved are closely correlated with the tumor-free non-SNs. Our data will assist such patients regarding the need for axillary dissection after finding a positive SN.