Transoral laser microsurgery for glottic cancer: landmark 24-year single-institution experience with 661 patients and validation of the isoprognostic zone system.

[BACKGROUND] Transoral laser microsurgery (TOLMS) is a cornerstone organ-preserving treatment for early and selected intermediate glottic squamous cell carcinoma (LSCC). Prognostic value of infiltration patterns remains underexplored. We evaluated long-term outcomes and validated the isoprognostic zone (IZ) system in a large monocentric cohort.

[METHODS] We retrospectively analyzed 661 patients with pT1-pT3 LSCC treated with TOLMS between 2000 and 2024. Endpoints were overall (OS), disease-specific (DSS), disease-free (DFS), laryngectomy-free survival (LFS), laryngeal preservation rate (LPR), and local control with laser alone (LCL). Prognostic factors were assessed with Kaplan-Meier and Cox regression, supported by Weibull accelerated failure time models.

[RESULTS] Median follow-up was 64 months. The 5-year LPR was 94.7%, with only 5.3% of patients undergoing total laryngectomy. Both pT stage and IZ independently predicted OS, DSS, DFS, and LFS. High-risk IZ classes were consistently associated with worse survival and laryngeal failure. Positive margins markedly increased recurrence and disease-specific mortality, but timely second-look surgery restored outcomes comparable to margin-negative cases.

[CONCLUSIONS] TOLMS provides durable oncologic control and high preservation rates in early to intermediate glottic LSCC. IZ refines prognostication beyond pT, with class VI highlighting anterior commissure infiltration as a decisive risk factor. Prompt second-look surgery is essential to safeguard true laryngeal preservation.