Prediction of Metastasis to Non‐sentinel Nodes by Sentinel Node Status and Primary Tumor Characteristics in Primary Breast Cancer in Taiwan

Abstract

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.