DO OVERALL TREATMENT TIME, FIELD SIZE, AND TREATMENT ENERGY INFLUENCELOCAL-CONTROL OF T1-T2 SQUAMOUS-CELL CARCINOMAS OF THE GLOTTIC LARYNX

Purpose: To evaluate treatment and patient related prognostic factors that may influence local control in the treatment of T1-T2 squamous ce ll carcinoma of the glottic larynx. Methods and Materials: One hundred nine patients with invasive, previously untreated T1-T2 squamous cell carcinoma of the glottic larynx were treated with curative intent wit h radiotherapy at the Fox Chase Cancer Center between June 1980 and No vember 1991. Follow-up ranged from 26-165 months (mean 83 months). Res ults: The 2-year local control rates for patients with T1 and T2 lesio ns were 89% and 80%, respectively. The 2-year local control rate for p atients whose overall treatment time was < 50 days was 92% vs, 82% for patients whose overall treatment time was > 50 days (p = 0.07). The 2 -year local control rate for patients treated with an irradiated area < 36 cm(2) was 90% compared to 86% in patients who were treated to an area greater than or equal to 36 cm(2). The 2-year local control rate for patients treated with Co-60 was 83% vs. 92% for patients treated w ith 6 MV x-ray. Cox proportional hazards regression analysis was perfo rmed using the following variables: treatment energy, irradiated area, gender, tobacco pack years, tumor differentiation, overall treatment time, total dose, dose per fraction, and T stage. Overall treatment ti me (p = 0.05) was the only variable that significantly influenced loca l control, Conclusion: Extending the overall treatment time was found to adversely influence local control, Neither the irradiated area nor treatment energy was found to influence local control in early stage v ocal cord carcinoma.