Assessment of intraoperative axillary sentinel lymph node biopsy - Upfront versus post neoadjuvant therapy

Objective: To assess the sensitivity of frozen section in the evaluation of sentinel lymph nodes in upfront and post neo-adjuvant cases of breast cancer. Material and Methods: This cross-sectional study was done at Liaquat National Hospital Karachi from January 2020 to September 2022. It included 420 patients who underwent breast surgeries upfront and post neo-adjuvant status whose one or more sentinel lymph nodes (SLN) were sent for frozen section (FS). Specimens received in formalin for FS and autolysed specimens were excluded. Axillary SLNs were sectioned at 2mm intervals perpendicular to the long axis and submitted. At least four frozen tissue sections of each block were examined. SLNs were further examined on permanent sections stained with hematoxylin and eosin (H&E). The results of intraoperative FS and permanent sections were compared. Results: Axillary SLNs of 420 patients sent for FS included 233 (55.5%) upfront cases and 187 (44.5%) post neo-adjuvant cases. FS detected sentinel lymph node metastasis in 118 (28.1%) patients while permanent sections detected metastases in 124 (29.5%) patients. Hence, out of the 6 (1.43%) false negative results, 3 (0.71%) were upfront and 3 (0.71%) were post neo-adjuvant cases. There was one false positive result in which a case of intraductal papilloma was misinterpreted as metastatic cancer on frozen section. Conclusion: The accuracy, sensitivity and specificity of frozen section indicates that the intraoperative examination of axillary SLNs by frozen section is equally reliable in both post neo-adjuvant and upfront cases of breast cancer. Keywords: Breast cancer, Frozen section, Post neo-adjuvant, Sentinel lymph node biopsy