Refining prognostic subcategories in intermediate-advanced glottic cancer: A multicentric study on 637 patients treated by transoral laser microsurgery.

Background: The current TNM staging system does not fully address the variations in glottic squamous cell carcinoma (SCC) extension and subsites involvement, especially if treated with transoral laser microsurgery (TOLMS). This study aims to evaluate the oncologic outcomes after TOLMS in intermediate-advanced glottic SCC, stratified by prognostic subcategories based on anatomical tumor extension.

Methods: This retrospective multicentric study analyzed 637 previously untreated patients with pT2-T3 glottic SCC treated by TOLMS following the same policies at four tertiary European centers. Patients were stratified into 5 subcategories (III, IV, Va, Vb, VI) based on three-dimensional local tumor extension, a refined definition of the previous classification proposed by Piazza et al. RESULTS: Out of 637 patients, 453 (71 %) were pT2, and 184 (29 %) pT3. The 5-year disease-specific survival for the entire cohort was 91 %, LCL 81 %, and LP 87 %. Subcategories Va (anterior paraglottic space [PGS] involvement) and Vb (posterior PGS involvement) showed significantly poorer disease-specific survival (Va: 91 %, Vb: 80 %) and local control with laser alone (Va: 76 %, Vb: 68 %) compared to subcategories III (tumors extending superficially to the supra- and/or subglottis) and IV (tumors infiltrating the vocal muscle). Tumors with posterior PGS involvement demonstrated the highest risk of local recurrence and total laryngectomy (HR: 3.70).

Conclusion: TOLMS is a viable treatment option for T2-T3 glottic SCC, offering high rates of laryngeal preservation and favorable oncologic outcomes in well-selected patients. Stratification based on tumor subsites involvement provides critical prognostic insights, with posterior PGS invasion serving as a key risk factor for poorer outcomes.