Is axillary dissection mandatory following a positive sentinel node biopsy?

Layfield, David and Cutress, Ramsey I. (2010) Is axillary dissection mandatory following a positive sentinel node biopsy? Advances in Oncology, 5 (4), 7-17.

Abstract

Management of the axilla in breast cancer has evolved rapidly following the implementation of sentinel lymph node biopsy (SLNB). Histological examination of the sentinel node allows accurate prediction of the overall stage of the axilla in 97% of patients [1-5]. Following SLNB, approximately 25-30% of patients will be identified as having a positive biopsy [3,6,7].

Current guidance from the American Joint Committee on Cancer (A]CC) [8] classifies axillary lymph node tumour deposits from a breast primary as macro metastasis, micro metastasis or isolated tumour cells (ITC). ITCs are single cells or small clusters of cells no greater than 0.2 mm in largest dimension, in the presence of which the node is classified as negative. AJCC staging distinguishes between ITC-positive [pNO (i+)] and ITC-negative [pN0(i-)] nodes; however, in the absence of proven benefit of intervention for ITC, current guidelines suggest equivalent management of these two groups [8,9].

Metastasis within a sentinel lymph node (SLN) is, conventionally, an indication for axillary clearance. Increased early breast cancer detection, more rigorous sectioning protocols and use of techniques such as immunological staining have increased the frequency with which micro metastasis and ITC are identified in the absence of concomitant macrometastatic disease. Published guidelines currently suggest treating axillae with sentinel nodes positive for micro metastasis but not in cases with ITC alone [9]. Despite this, significant variation in practice still exists; some groups advocate surgical management whenever tumour material within the sentinel node is identified, regardless of size. Others suggest selective avoidance of completion axillary lymph node dissection (cALND) following identification of micrometastatic disease in low-risk patients [10].

This paper reviews the evidence for performing axillary lymph node dissection (ALND), the reported incidence of sentinel and associated non-sentinel lymph node metastasis, the methods employed in prediction of non-sentinel lymph node (NSLN) metastasis and whether alternative treatment strategies following positive SLNB might rationalise current surgical management.

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