PROGNOSTIC FACTORS FOR LOCAL-CONTROL AND SURVIVAL IN T1 SQUAMOUS-CELLCARCINOMA OF THE GLOTTIS

Purpose: To evaluate the effect of host, tumor, and treatment-related variables on local control and survival in patients with T1N0M0 squamo us cell carcinoma of the glottis. Materials and Methods: Ninety-one pa tients with T1N0M0 squamous cell carcinoma of the glottic larynx were analyzed. Median follow-up was 9 years (range 2-25). Patients were tre ated with daily fractions of 180 cGy to 220 cGy to doses of 5925-7000 cGy (median 6400). The following factors were analyzed: age, sex, hist ologic grade, disease extent, beam energy, field size, total dose, dos e per fraction, and elapsed treatment days. Results: The 5-year actuar ial local control was 80%. On univariate analysis, only elapsed treatm ent days and dose per fraction were significant factors for local cont rol. Local control was 100% if treatment was completed within 42 days, 91% for 43-46 days, 74% for 47-50 days, 65% for 51-54 days, and 50% f or 55-66 days (p = 0.0001). In patients treated at < 200 cGy per fract ion, local control was 62% as compared to 87% for greater-than-or-equa l-to 200 cGy per fraction (p = 0.006). On multivariate analysis, only elapsed treatment days was a significant factor for local control (p = 0.0001). The 5-year actuarial survival for the whole group was 92%. E lapsed treatment days was the only variable affecting survival. Surviv al was 100% if treatment was delivered within 42 days, 96% for 43-46 d ays, 94% for 47-50 days, 91% for 51-54 days, and 67% for 55-66 days (p = 0.02). The 5-year actuarial disease-specific survival was 95%, with treatment duration again being the only significant prognostic factor . Disease-specific survival was 97% for treatment completed within 39- 54 days versus 80% for 55-66 days (p = 0.02). Only three (3.3%) patien ts experienced moderate or severe complications. None of the evaluated parameters impacted significantly on complications. Conclusion: We co nclude that elapsed days is the most prognostically significant factor for local control and survival in patients treated with radiotherapy for T1 squamous cell carcinoma of the glottis. We recommend that these patients be treated with 210 cGy daily fractions to 6300 cGy.