The Extent of Axillary Lymph Node Clearance Required Following Detection of Sentinel Node Micrometastases.

Sentinel node (SN) micrometastases are an indication to proceed to axillary clearance. The aim of this study is to determine the extent and level of axillary clearance required for patients with SN micrometastases. All patients with SN micrometastases which were followed by axillary clearances from 1999 to 2007 were identified. Slides were reviewed by a histopathologist to detail characteristics of SN micrometastases including size and site. The SN micrometastases and primary tumor characteristics were correlated with the presence and level of non-SN micrometastases. Fifty patients who had micrometastases followed by axillary clearances were identified. Of those 18% (n = 9) had non-SN metastases.Seven patients had metastases to level I, one patient had metastases to level I and III and one patient had non-SN metastases to level III only. No patient had metastases to level II. Patients with non-SN metastases had very limited number of non-SNs involved (maximum 2 non-SNs). No variable, including site of the micrometastasis, was predictive of non-SN metastases. In patients with SN micrometastases, a limited level I axillary clearance can be justified in view of the low number of additional nodes involved and in particular, the low (4%) rate of spread to level II ⁄ III nodes.