A practical approach to intraoperative evaluation of sentinel lymph node biopsy in breast carcinoma and review of the current methods.

Background: Sentinel lymph node (SLN) biopsy is increasingly becoming an alternative method for assessing axillary status in breast carcinoma patients. Intraoperative SLN evaluation can potentially select patients for immediate axillary clearance and spare most of them a second surgical procedure. Nevertheless, no standard protocol for intraoperative SLN evaluation has been developed. The aims of this study were to establish the reliability of SLN intraoperative evaluation in breast carcinoma staging, to review the published methods currently used, and to propose a standard protocol.

Methods: One hundred fifty-two SLNs were collected from 86 patients. Lymphoscintigraphy, blue dye, and gamma camera intraoperative controls were used for localization. Each SLN was sliced 2 mm thick and was intraoperatively evaluated by using the combination of frozen section and imprint cytology. The final examination included standard hematoxylin and eosin staining, and, in case of persistent negativity, further sectioning, including hematoxylin and eosin combined with immunohistochemistry (CAM5.2 cytokeratin), was performed.

Results: The combination of frozen section and imprint cytology for intraoperative SLN evaluation yielded an intraoperative sensitivity of 78% and a specificity of 100%. All macrometastases (>2 mm) were detected during surgery, as were 2 micrometastases. Final examination detected seven more micrometastases, six of which consisted of isolated tumor cells.

Conclusions: We propose a fast, cost-effective, and accurate procedure for SLN evaluation that is useful for making intraoperative decisions, feasible for most institutions, and reliable because of its high sensitivity (100% for macrometastases) and specificity.