Long-Term Outcome of Definitive Radiotherapy for Early Glottic Cancer: Prognostic Factors and Patterns of Local Failure

PURPOSE: This study evaluates the long-term results of definitive radiotherapy (RT) for early glottic cancer. Clinical and treatment factors related to local control and patterns of failure are analyzed. MATERIALS AND METHODS: We retrospectively reviewed 222 patients with T1-2N0 squamous cell carcinoma of the glottic larynx treated with definitive RT from 1981 to 2010. None of the patients received elective nodal RT or combined chemotherapy. The median total RT dose was 66 Gy. The daily fraction size was < 2.5 Gy in 69% and 2.5 Gy in 31% of patients. The RT field extended from the hyoid bone to the cricoid cartilage. RESULTS: The median age was 60 years, and 155 patients (70%) had T1 disease. The 5-year rates of local recurrence-free survival (LRFS) and ultimate LRFS with voice preservation were 87.8% and 90.3%, respectively. T2 (hazard ratio [HR], 2.30; 95% confidence interval [CI], 1.08 to 4.94) and anterior commissural involvement (HR, 3.37; 95% CI, 1.62 to 7.02) were significant prognostic factors for LRFS. In 34 patients with local recurrence, tumors recurred in the ipsilateral vocal cord in 28 patients. There were no contralateral vocal cord recurrences. Most acute complications included grade 1-2 dysphagia and/or hoarseness. There was no grade 3 or greater chronic toxicity. CONCLUSION: Definitive RT achieved a high cure rate, voice preservation, and tolerable toxicity in early glottic cancer. T2 stage and anterior commissural involvement were prognostic factors for local control. Further optimization of the RT method is needed to reduce the risk of ipsilateral tumor recurrence.