The records of all patients with T2, NO squamous cell carcinoma of the true vocal cords treated with definitive radiotherapy at The University of Texas M. D. Anderson Cancer Center between 1970 and 1985 were analyzed to investigate treatment outcome, prognostic factors associated with tumor recurrence, and the potential impact of improved initial treatment on patient survival. There were 114 patients (male to female ratio, 13:1) with a median age of 62 years at presentation. All were treated with external beam irradiation to a modal dose of 70 Gy in 35 fractions over 7 weeks. The median field size was 25 cm2 and no elective treatment to the neck was routinely given. The crude recurrence rate after definitive radiotherapy was 32%. Of the 37 local regional failures, 32 were in the larynx only, 3 in the neck, and 2 in both the larynx and the neck. All patients who had recurrence after radiotherapy underwent salvage procedures, which increased the ultimate control rate above the clavicles to 94%. Overall and disease-specific survival rates at 5 years were 69% and 92%, respectively. Fifty patients died: 7 of laryngeal cancer, 2 of complications of salvage surgery, 13 of unrelated second cancers, and 28 of other intercurrent disease. The prospects for improved survival through more effective initial treatment of this stage of glottic cancer are therefore very limited. Significant complications of radiotherapy occurred in only 4 patients (3.5%), and overall, 74% of patients retained a functional larynx. Analysis of a wide variety of patient-, tumor-, and treatment-related variables failed to identify any statistically significant prognostic factors.(ABSTRACT TRUNCATED AT 250 WORDS)