Breast Sentinel Lymph Node Frozen Section Practice: An Enterprise Audit as a Guide for Moving Forward.

* Context.--In recent years, there has been a shift to less aggressive surgical management of the axilla in breast cancer. Consequently, sentinel lymph node evaluation by frozen section (FS) has declined. Additionally, there has been an impetus to decrease efforts in identifying small sentinel lymph node metastases. Objectives.--To critically evaluate our enterprise performance in evaluating axillary sentinel lymph nodes submitted for FS prior to considering changes in processing. Design.--A retrospective review (August 1, 2017-July 31, 2019) was conducted to identify sentinel and nonsentinel lymph nodes from 1 academic institution and 2 community sites. Cases were evaluated for grossing technique and discordance between FS and permanent section (PS) due to sampling and/or interpretive error. Clinicopathologic features were assessed. Results.--Lymph nodes from 426 patients with 432 neoplasms were sent for FS. Serial sectioning at 2-mm intervals was adhered to in 338 of 432 (78.2%). Serial sectioning was significantly lower at the community sites (14 of 60; 23.3%) versus at the academic institution (324 of 372; 87.1%; P < .001). Discordant cases were all false negatives (21 of 432; 4.8%). A total of 7 of 21 false negatives (33.3%) had macrometastatic (>2 mm) disease; of these, 3 were post--neoadjuvant chemotherapy, 3 were neither serially sectioned nor posttherapy, and 1 was a small (0.3-cm) focus. A total of 15 of 16 false negatives due to sampling error were detected on the first permanent section level. Conclusions.--Standard serial sectioning of sentinel lymph nodes at 2-mm intervals resulted in infrequent false negatives due to macrometastatic disease. A single additional permanent section level is reasonable, given adherence to serial sectioning. [ABSTRACT FROM AUTHOR]