Discordance of Intraoperative Frozen Section Analysis with Definitive Histology of Sentinel Lymph Nodes in Breast Cancer Surgery: Complementary Axillary Lymph Node Dissection is Irrelevant for Subsequent Systemic Therapy

Background. In breast cancer surgery, intraoperative frozen section (FS) analysis of sentinel lymph nodes (SLNs) enables axillary lymph node dissection (ALND) during the same operative procedure. In case of discordance between a "negative" FS analysis and definitive histology, an ALND as a second operation is advocated since additional lymph node metastases may be present. The clinical implications of the subsequent ALND in these patients were evaluated. Materials and Methods. Between November 2000 and May 2008, 879 consecutive breast cancer patients underwent surgery including sentinel lymph node biopsy (SLNB) with intraoperative FS analysis of 2 central cuts from axillary SLNs. Following fixation and serial sectioning. SLNs were further examined postoperatively with hematoxylin and eosin (H&E) and immunohistochemical techniques. For patients with a discordant FS examination, the effect of the pathology findings of the subsequent ALND specimen on subsequent nonsurgical therapy were evaluated. Results. FS analysis detected axillary metastases in the SLN(s) in 200 patients (23%), while the definitive pathology examination detected metastases in SLNs in another 151 patients (17%). A complementary ALND was performed in 108 of the 151 patients with discordant FS. Additional tumor positive axillary lymph nodes were found in 17 patients (16%), leading to "upstaging" in 7 (6%). Subsequent nonsurgical treatment was adjusted in 4 patients (4%): all 4 had more extensive locoregional radiotherapy; no patient received additional hormonal and/or chemotherapy. Conclusion. Discordance between intraoperative FS analysis and definitive histology of SLNs is common. In this selection of patients. a substantial proportion had additional lymph node metastases, but postsurgical treatment was rarely adjusted based on the findings of the complementary ALND.