Intraoperative diagnosis of breast cancer metastasis in axillary lymph nodes: Cytological Smear vs. Frozen Section

•Cytological smear allows intraoperative assessment of sentinel lymph nodes.•In this study, the precision of cytological smear was comparable to frozen section.•Only 1 of 51 patients evaluated, had a false negative result. Intraoperative evaluation of axillary lymph nodes is sometimes required to determine the extent of surgery. In this study, we wished to assess the reliability of cytologic smear (CS) in determining lymph node involvement with tumor. Theoretically, CS provides more substance for examination than touch-imprint cytology and is faster to perform than frozen section (FS). We hypothesized that CS sensitivity for tumor cell detection in the lymph nodes would be similar to FS, at least 0.90. This was a retrospective observational study at the Rambam Health Care Campus (January, 2013-June, 2020). Lymph nodes underwent intraoperative evaluation using either CS or FS, based on the availability of a cytologist at the time of the examination. Both intraoperative evaluations were compared to the final pathology following fixation with formalin. Eighty-eight patients undergoing intraoperative analysis were analyzed (51 CS, 37 FS). False-negative tests were recorded in only 1 patient evaluated by each of the 2 methods. This resulted in sensitivity 0.91 (95%CI 0.59, 1.00) for CS and 0.88 (95%CI 0.47, 1.00) for FS, specificity 1.00 (95%CI 0.91, 1.00) for CS and 1.00 (95%CI 0.88, 1.00) for FS, positive predictive value 1.00 (95%CI 0.69, 1.00) for CS and 1.00 (95%CI 0.59, 1.00) for FS, and negative predictive value 0.98 (95%CI 0.87, 1.00) for CS and 0.97 (95%CI 0.83, 1.00) for FS. The sensitivity of the CS in this study is comparable to that of FS and due to shorter analysis time required is the preferred method at our institution. We assessed the reliability of cytologic smear (CS) in determining lymph node involvement with tumor. Fifty-one patients undergoing intraoperative analysis were analyzed. CS had a sensitivity 0.91, specificity 1.00, positive predictive value 1.00, and negative predictive value 0.98. The precision of the CS in this study was comparable to that of 37 patients evaluated with frozen section.