Sensitivity and Predictive Value of the Frozen Section of Sentinel Lymph Node Biopsy in the Post-neoadjuvant Setting: Experience From a Tertiary Care Hospital in a Resource-Limited Country

Background Axillary lymph node status is one of the most important prognostic factors in breast cancer treatment, which can be confirmed by sentinel lymph node biopsy (SLNB). Intraoperative frozen section is an alternative method for SLNB, which can reduce the risks associated with secondary surgery. The feasibility and accuracy of SLNB after post-neoadjuvant chemotherapy (NACT) are affected by many factors as lymphatic drainage from the breast could be impaired due to fibrosis, fat necrosis, and granulation tissue formation, thus hampering the detection of the sentinel lymph node and afterward interpretation by pathologists due to therapy-related changes. Despite the increasing use of SLNB in post-NACT settings, there is still limited information on the accuracy of SLNB in resource-limited countries. Objective Our study aims to detect the sensitivity and predictive value of frozen section SLNB in the post-NACT setting while comparing it with final permanent histopathological results and considering final permanent histopathological results as standard. Materials and methods A total of 286 patients meeting the inclusion criteria from 2021 to 2022 were included in the study. Hematoxylin and eosin (H&E)-stained microscopic glass slides of frozen SLNB after NACT, permanent paraffin-embedded sections, and immunohistochemical stains were retrieved and reviewed. For all the categorical variables, including histologic type and grade, frequencies and percentages were obtained. Measures of central tendency and variability for continuous data such as age, number of sentinel lymph nodes received, and size of the largest nodal deposit were calculated. The chi-square test was used for the comparison of qualitative variables. A p-value of less than or equal to 0.05 was considered statistically significant. Results The median age of presentation was 47 years (range = 39 to 55 years). The median number of sentinel lymph nodes received was three (range = 2-4). At the time of frozen section reporting, out of a total of 286 cases, 229 (80.1%) cases were labeled as negative, 55 (19.2%) cases as positive, and two (0.7%) cases were deferred for permanent section results. Out of 229 cases labeled as negative at the time of the frozen section, 220 (76.9%) cases were true negative confirmed on permanent sections. A total of 66 (33.1%) cases were true positive, including two deferred cases and nine false negative cases, in addition to 55 cases labeled as positive on the initial frozen section. The study showed sensitivity, specificity, and accuracy of frozen section analysis of SLNB at 83.00%, 100%, and 96.15%, respectively, with a false negative rate (FNR) rate of 16.7%. Conclusion Further follow-up studies to definitively determine the role of SLNB following post-NACT in patients who did not undergo axillary lymph node dissection (ALND) are needed. Continuous monitoring of the rate of false positives and false negatives of frozen sections on SLNB is essential as feedback for pathologists.