T1-T2 SQUAMOUS-CELL CARCINOMA OF THE GLOTTIC LARYNX TREATED WITH RADIOTHERAPY - A MULTIVARIATE-ANALYSIS OF VARIABLES POTENTIALLY INFLUENCING LOCAL-CONTROL

Purpose: To examine various parameters that might influence the probability of local control of T1-T2 glottic carcinoma treated with radiotherapy. Methods and Materials: Two hundred forty-seven patients with invasive, previously untreated T1-T2 squamous cell carcinoma of the glottic larynx were treated with radiotherapy between May 1977 and December 1989. All patients had a minimum 2-year follow-up. To minimize treatment-related variables, only patients with Tl lesions treated once daily at 225 cGy per fraction and patients with T2 lesions treated once daily at 225 cGy per fraction or twice daily at 120 cGy per fraction were included. Surgical alternative, thickness of the neck at the posterior edge of the lateral fields, vocal cord mobility, anterior commissure involvement, gender, and T stage were evaluated in a multivariate analysis. Results: The 5-year local control rates, calculated by the product-limit method, were T1a, 95%; T1b, 96%; T2a, 87%; and T2b, 76%. The 5-year local control rate for patients with T2 lesions treated with once-daily fractionation was 81% compared with 91% for those who received twice-a-day radiotherapy. For the endpoint of local control with irradiation, the surgical alternative (p = .020) and cord mobility (p = .001) were of independent prognostic significance. Conclusion: Of the variables analyzed, only vocal cord mobility and surgical alternative significantly influenced local control. Specifically, anterior commissure involvement and neck thickness did not affect local control.