Extensive frozen section examination of axillary sentinel nodes to determine selective axillary dissection

As experience accumulates on the use of sentinel node biopsy in breast canc er, it is becoming clear that the method can reliably predict the state of the axilla and thus be used to decide whether to perform complete axillary dissection. Ongoing controlled trials will soon provide definitive evidence on the latter point. The key issue regarding sentinel node biopsy is patho logic evaluation of the biopsied node, which should be done intraoperativel y whenever possible. In our initial experience with a conventional intraope rative frozen section method, the false-negative rate was 19% compared to e xamination of permanent sections of the biopsied node. We therefore devised a new intraoperative method in which pairs of sections are obtained every 50 mum for the first 15 sections and every 100 mum for any remaining node, which essentially samples the entire node; the method takes about 10 minute s. Sentinel node metastases were found in 119 of 295 (40%) of T1N0 breast c ancer patients examined by this new method. This high rate of positivity in dicates that the new method is reliable. In all cases, metastases were iden tified on hematoxylin-eosin (HE)-stained sections, although in 4% of positi ve cases the HE sections were doubtful, and cytokeratin immunostaining on t he adjacent section was useful for confirming malignancy. Of 295 patients, 8 (2.7%) had a negative sentinel node but another axillary node metastasis. In conclusion, we found that extensive intraoperative frozen section exami nation of sentinel nodes correctly predicts a metastasis-free sentinel node in 95.4% of cases (negative predictive value), it is therefore suitable fo r identifying patients in whom axillary dissection might be avoided. Immuno cytochemical staining for cytokeratins or other epithelial markers may be h elpful for reducing the risk of missing micrometastatic foci.