Evaluation of immunohistochemistry and multiple-level sectioning in sentinel lymph nodes from patients with breast cancer.

CONTEXT: Previous investigations on sentinel lymph node biopsies have demonstrated their importance in nodal staging of patients with breast cancer. However, sentinel node biopsy in breast cancer is currently a controversial procedure and continues to provoke debate.
OBJECTIVES: We designed our study to determine the usefulness of a standard protocol for evaluating sentinel lymph node metastases and to assess the value of sentinel node biopsy as the only procedure in nodal staging in breast cancer patients.
MATERIALS AND METHODS: A retrospective analysis of 84 breast cancer patients with sentinel node biopsies, who also underwent axillary dissection, was conducted using a standard protocol (3 levels of immunohistochemical stains for keratin and 2 levels of hematoxylin-eosin (HE) stains on the first 3 negative lymph nodes).
RESULTS: Hematoxylin-eosin staining identified 20 patients (23.8%) with sentinel node metastases. The remaining 64 negative patients (76.1%) were tumor free on sentinel lymph nodes at level 1 HE. Additional immunohistochemical stains for keratin and HE stains on specimens from these 64 patients showed an additional 5 patients (7.8%) to be positive for lymph node micrometastases (<2 mm). The total percentage of cases with sentinel lymph node metastases detected by HE staining and immunohistochemistry was 29.7%. Of the remaining 59 cases that were negative on HE and immunohistochemistry, axillary dissection revealed 3 cases that had metastases in the axillary lymph nodes. The false-negative rate was 10.7%. The concordance rate between sentinel lymph nodes and axillary lymph nodes was 96.4%. The sensitivity was 89% and specificity was 100%.
CONCLUSION: Immunohistochemistry and multiple-level sectioning increased detection of metastases by 7.8% in sentinel lymph nodes. Caution should be used in accepting sentinel node biopsy alone as the only procedure for staging due to a high false-negative rate (10.7%). A predictive value of 96.4% confirms that sentinel lymph node biopsy is most likely to contain metastatic carcinoma. Sentinel lymph node examination with the protocol we describe, combined with axillary dissection, increased the yield of metastatic disease by identifying 8 additional cases of nodal metastatic disease (an increase of 28%), as compared to standard axillary nodal dissection and single-section sentinel lymph node examination alone.