Definitive radiotherapy for early stage glottic cancer: a quarter-century of single-institution experience with long-term outcomes and late events

BACKGROUND: Definitive radiotherapy is a standard organ-preserving treatment for early-stage glottic cancer; however, real-world data describing very late adverse events after long-term follow-up remain limited. METHODS: We retrospectively analyzed consecutive patients with stage I–II glottic squamous cell carcinoma treated with definitive external beam radiotherapy at a single institution over a 25-year period. Endpoints included overall survival (OS), cancer-specific survival (CSS), disease-free survival (DFS), and local control (LC). Time-to-event outcomes were estimated using the Kaplan–Meier method. The cumulative incidence of grade ≥ 3 adverse events was estimated with death as a competing risk, with vascular events and laryngeal necrosis–related events analyzed separately. RESULTS: A total of 257 patients were included (median age, 70 years; 93% male); 169 (66%) had stage I and 88 (34%) had stage II disease. Median follow-up was 61.2 months (range, 3.0–265.7). In the overall cohort, OS at 5, 10, and 15 years was 86.5%, 81.8%, and 73.8%, respectively. DFS at 5 years was 81.7% in stage I and 67.5% in stage II (p = 0.0409). LC at 5 years was 89.6% in stage I and 82.0% in stage II (p = 0.154). Ten grade ≥ 3 adverse events were recorded, with a median time to onset of 95.0 months. The cumulative incidence of any grade ≥ 3 adverse event was 1.9% at 5 years and 4.6% at 10 years. Vascular events occurred in 8 patients (5-year 1.1%; 10-year 3.8%), while grade ≥ 3 laryngeal events occurred in 2 patients (0.8% at both 5 and 10 years). CONCLUSIONS: In this quarter-century real-world cohort, definitive radiotherapy for stage I–II glottic cancer achieved durable long-term outcomes with a limited incidence of severe late adverse events. The long latency of events, particularly vascular complications, refers the importance of extended survivorship follow-up and vigilant monitoring for uncommon but clinically meaningful late toxicity.