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.