Twenty-nine patients with previously untreated T3 squamous cell carcinoma of the glottic larynx were treated for cure with radiotherapy alone; all had a minimum 2-year follow-up. High-quality pretreatment computed tomography scans were retrospectively reviewed by a single head and neck radiologist for tumor involvement of various anatomic subsites within the larynx, and total tumor volumes were calculated for 18 of the most recent patients using a computer digitizer