A Retrospective Study to Assess the Accuracy of Frozen Sections in Laser Laryngeal Surgery

The basis of good vocal outcomes following Transoral Laser Microlaryngeal Cordectomy (TLMC) is the narrow margin that is oncologically accepted for the glottis. Our objective is to evaluate the reliability of frozen section (FS) compared to paraffin section (PS) during TLMC and during laser laryngeal surgery when an incisonal or excisional biopsy is being performed.

Retrospectively, records of 159 sequential patients who underwent CO₂ laser laryngeal surgery with intraoperative FS were reviewed along with the final PS. Group A patients were TLMC patients where FS was utilized for free margin confirmation (42 specimens) and Group B patients were those in whom FS was performed for primary diagnosis (122 specimens).

A total of 164 samples were included where specimens submitted for FS were also processed for PS. Concordance was observed in 156 samples, discordance in 8, with 4 cases belonging to each group. FS was reported as false negative in 5 and false positive in 3 cases. In Group A where FS was utilized for free margin confirmation, the sensitivity was found to be 60%, specificity and positive predictive value (PPV) 100%, and negative predictive value (NPV) 88.9%. In Group B where FS was performed for primary diagnosis, the sensitivity was found to be 98.4%, specificity 95.1%, PPV 95.2%, and NPV 98.3%.

A 100% PPV of FS in group A suggests that positive FS margins during TLMC may be safely relied upon in making decisions to upgrade the type of cordectomy being performed. A NPV of 88.9% in group A suggests that despite a clear frozen margin report during TLMC, 11.1% of patients would need further treatment. A PPV of 95.2% in group B suggests that although FS analysis is important for guiding further management, decisions regarding major laryngeal surgery should not be undertaken based solely on FS.