Background: The goal of intraoperative sentinel lymph node (SLN) examination is to avoid reoperation for a positive SLN, but the ideal method of intraoperative SLN examination remains unclear, and published results vary widely.
Methods: We evaluated the sensitivity of intraoperative frozen section (FS), touch preparation (TP), and cytological smear (CS) in 305 SLNs from 133 breast cancer patients. Each SLN was received fresh and cut into 2- to 3-mm slices; TP and CS from each cut surface and an FS of the entire SLN were obtained. Postoperative evaluation of the SLN consisted of 1 hematoxylin and eosin-stained section and of one hematoxylin and eosin-stained and one immunohistochemically stained section for cytokeratin from each of two levels 50 microm apart. Tumor cells found by any method, including immunohistochemistry, identified a positive SLN. Three pathologists blinded to the final SLN diagnosis reviewed all TP, CS, and FS; the consensus diagnosis (concordance of two or more) was used for the study.
Results: FS, TP, and CS had comparable sensitivities (59%, 57%, and 59%, respectively). Each method was more sensitive in detecting macrometastases (>2 mm; 96%, 93%, and 93%, respectively) than micrometastases (< or =2 mm; 27%, 27%, and 30%, respectively). The combination of methods only marginally improved the intraoperative sensitivity. TP and CS were each responsible for a single false-positive result.
Conclusions: FS, TP, and CS are comparable for the intraoperative detection of SLN metastases, and each method is substantially better at detecting micrometastases than micrometastases. The combination of two or more techniques only marginally improves the sensitivity over that achieved by a single method.