Can pretreatment CT predict local control of T2 glottic carcinomas treated with radiation therapy alone?

PURPOSE To determine whether pretreatment CT can predict local control of T2 squamous cell carcinoma of the glottic larynx treated with radiation therapy alone. METHODS Pretreatment CT studies were retrospectively evaluated by two head and neck radiologists in 28 patients with T2 squamous cell carcinoma of the glottic larynx treated with definitive radiation therapy. All patients were followed for a minimum of 2 years. A tumor score was calculated based on the CT findings of tumor involvement of the following areas: the anterior commissure, the contralateral true vocal cord, the arytenoid face, the interarytenoid region, the laryngeal ventricle, the paraglottic space at the true and false vocal cord levels, and the subglottic region. Tumor volumes based on pretreatment CT were measured in each patient using a computer digitizer. Statistical analysis was performed using the independent sample t test, Wilcoxon's rank sum test, and Fisher's Exact Test. RESULTS There was no statistically significant relationship between tumor volume or tumor score and outcome of the T2 glottic tumors treated with definitive radiation therapy in this series. The overall local control rate was 82%. There were no treatment complications that resulted in loss of laryngeal function. CONCLUSIONS Like low-volume supraglottic and T3 glottic carcinomas, T2 glottic squamous cell carcinoma is likely (82%) to be controlled with definitive radiation therapy. Failure to control the primary tumor is attributable to factors other than volume, which may not be detectable on CT, such as tumor-host biological factors. Pretreatment CT, however, is beneficial for detecting submucosal spread across the ventricle and subglottic extension, which might contraindicate vertical hemilaryngectomy and might not be apparent on endoscopic examination.