RESUMO
AIMS: To determine the influence of dose and fractionation on tumour characteristics, toxicity, disease control and survival outcomes in T1 glottic carcinoma. MATERIALS AND METHODS: Between 1975 and 2000, treatment charts of 652 patients with T1 glottic carcinoma who received curative radiation with four hypofractionated schedules (50 Gy/15 fractions [3.3 Gy/fraction] or 55 Gy/16 fractions [3.43 Gy/fraction] or 60 Gy/24 fractions or 62.5 Gy/25 fractions [2.5 Gy/fraction]) were analysed. The patients were divided into two groups based on fraction size <3 Gy and >3 Gy. Local control and overall survival were calculated. Patient- and tumour-related factors affecting local control were analysed using univariate and multivariate analysis. Factors affecting late toxicity were also analysed. RESULTS: The local control and overall survival at 10 years were 84 and 86.1%, respectively, for T1 glottic carcinoma. The response to radiation had a significant effect on local control with univariate analysis (P = 0.001). Other factors, such as beam energy, anterior commissure involvement and fractionation, did not affect local control. Persistent radiation oedema was seen in 123 patients (23.4%) and was significantly worse in patients who received radiation with a larger field size (>36 cm(2)) on a telecobalt machine (P < 0.001). CONCLUSIONS: Radical radiotherapy schedules incorporating a higher dose per fraction yield acceptable local control rates and late toxicity. Telecobalt therapy for early glottic cancer is a safe alternative to treatment with 6 MV photons on a linear accelerator in terms of local control and late toxicity as long as field sizes smaller than 36 cm(2) are used.
