Reconsidering the Role of Intraoperative Frozen Section in Sentinel Lymph Node Biopsy for Mastectomy Patients with Early-Stage Breast Cancer: A 5-years retrospective review from King Chulalongkorn Memorial Hospital. 

Background and Aims: The trend of sending sentinel lymph node biopsy (SLNB) specimens for permanent section (PS) without intraoperative frozen sections (iFS) is increasing globally. This pilot study conducted in Thailand aimed to evaluate the role of intraoperative frozen section (iFS) in early-stage breast cancer patients who underwent mastectomy with SLNB. Methods: : A 5-year retrospective study of 1773 patients from December 2017 through 2022 was conducted in a tertiary care center in Thailand. The inclusion criteria were early-stage breast cancer patients with either radiologically negative nodes, or radiographically borderline nodes found to be negative on FNA in line with the AMAROS criteriawho underwent mastectomy and SLNB. Re-operations were indicated when 3 or more nodal metastases were detected on the pathological analysis. The re-operation rate prevented by iFS and the re-operation rate needed for those with PS alone were reported. Results: : Among 265 patients, 202 patients underwent concomitant iFS while the remaining 63 patients underwent PS alone. Six patients (3.0%) from the iFS group and 1 patient (1.6%) from the PS group were found with more than 2 nodal metastases. Despite using intraoperative frozen sections, only one patient from each group required reoperation. There was no significant difference in the number of patients requiring reoperation between the iFS group and the PS group. Conclusions: : Our study provides strong evidence to all surgeons in Thailand and low-to-middle income countries (LMIC) that in early breast cancer patients undergoing mastectomy, SLNB with PS analysis alone may not lower the standard of care compared to using additional iFS analysis. Adopting this practice may lead to decreased operation costs, operative time, and anesthetic side effects.