Intraoperative examination of sentinel lymph nodes by ultrarapid immunohistochemistry in breast cancer

Background: The ultrarapid immunohistochemistry (IHC) technique was applied to the intraoperative examination of sentinel lymph nodes (SLNs) because routine SLN frozen section examinations sometimes produce false-negative results. The present study was undertaken to develop a reliable protocol for the ultrarapid IHC of SLNs. Methods: SLNs from 79 breast cancer patients with clinically negative axillary node were examined intraoperatively by frozen hematoxylin-eosin (H&E) stain and by ultrarapid cytokeratin IHC assay. On the basis of the result of serially sectioned permanent study, the sensitivity and accuracy of each intraoperative technique were compared. Results: The total number of dissected SLNs was 178 with a mean of 2.3 (1-5) per patient. The mean turnaround time for ultrarapid IHC was 20 min. The sensitivity rates of frozen H&E staining and ultrarapid IHC were 70.0 and 85.0%, respectively (P = 0.083). Each method had a specificity of 100%. The accuracy rates for frozen H&E staining and rapid IHC were 92.4 and 96.2%, respectively (P = 0.083). Ultrarapid IHC detected one additional patient with sentinel node micrometastasis and two additional patients with isolated tumor cells (ITCs). In those patients, two underwent completion axillary dissection simultaneously and could avoid a second operation. Conclusions: Ultrarapid cytokeratin IHC enhanced the intraoperative detection of sentinel node micrometastasis and ITCs in breast cancer without consuming much time. In patients who need completion axillary dissection after sentinel node biopsy, this technique could be helpful in avoiding a second operation.