Intraoperative frozen section analysis of sentinel lymph node in breast cancer patients treated with neoadjuvant chemotherapy

Background: Recently, many studies have demonstrated the feasibility and accuracy of sentinel lymph node (SLN) biopsy for patients treated with neoadjuvant chemotherapy (NAC). However, no studies have been conducted to evaluate the accuracy of frozen section (FS) analysis of SLN in NAC-treated patients. The aim was to evaluate the accuracy of intraoperative FS analysis of SLNs in breast cancer patients treated with NAC in comparison with that in those not treated. Methods: Patients with primary breast cancer either treated with NAC (n = 62) or not treated (n = 301) were included in this study. Intraoperatively, the largest cut surface (2-mm thickness) of the SLN was subjected to FS analysis. Remainders of the SLN were formalin-fixed, serially sectioned at 2-mm thickness, and subjected to H&E staining and immunohistochemistry. The largest diameter of metastases in the SLN was measured. Results: The sensitivity, specificity, and accuracy of FS analysis of SLNs were 74, 100, and 88%, respectively, for NAC-treated patients, similar to the corresponding values of 71, 99, and 90% for non-NAC-treated patients. The sensitivity of FS analysis for macrometastases was lower for NAC-treated patients (76%) than for non-NAC-treated patients (91%), while that for micrometastases and isolated tumor cells was higher for NAC-treated patients (67%) than for non-NAC-treated patients (31%). However, neither of these differences was statistically significant. Conclusions: Intraoperative FS analysis of SLNs is as accurate for NAC-treated as for non-NAC-treated patients, indicating that FS analysis of SLNs is a clinically acceptable method for those receiving NAC.