The significance of immunohistochemistry positivity in sentinel nodes which are negative on haematoxylin and eosin in breast cancer

Abstract

Introduction Sentinel lymph node (SLN) biopsy allows a more detailed examination of a smaller number of lymph nodes in patients with clinically node negative breast cancer. Immunohistochemistry detects small tumour burden not routinely seen on haematoxylin and eosin (H&E). The significance of such findings remains to be fully elucidated. Aim To assess the axillary disease burden of patients in whom the sentinel lymph node biopsy was positive on immunohistochemistry and negative on H and E. Methods An analysis of patients who underwent SLN mapping for breast cancer at St Vincent's University Hospital from January 1st, 2000 to December 31st, 2006 was conducted. All SLNs were assessed by serial H&E and IHC sections. Patients with micrometastases (0.2–2 mm) underwent a completion axillary lymph node dissections (CLND). Patients with ITC (<0.2 mm) were individually discussed and a CLND was performed selectively based on additional clinicopathological criteria and patient preference. Analysis of the additional nodes from CLND was performed. Patients were followed for a median of 27 months (range 12–72 months). Results 1076 patients who underwent SLN were included for analysis. 211 (20%) had a positive SLN biopsy using H&E. Forty-nine patients (5%) had a negative SLN on H&E which was positive on IHC. Of these, 15 had micrometastases and underwent a CLND. Two had further axillary nodal disease. ITC were found in the remaining 34 patients. Sixteen of these patients underwent a CLND. Five of this group had further nodal disease. Conclusion Micrometastases and isolated tumour cells, detected only by immunohistochemical analysis of sentinel lymph nodes, are associated with further positive nodes in the axilla in up to 15% of patients. This upstaging of disease may impact upon patient outcome.