Radiotherapy of T1 glottic cancer with 6 MeV X rays.

We treated 154 patients with T1 glottic carcinoma with 6 MeV X rays through 16 cm2 parallel-opposing open fields on a free set-up delivering a median dose of 67 Gy in 6 2/3 weeks. Observed and relative 5-year survival rates for all patients were 87% and 100%, respectively. The local control rate at 5 years was 89%. Of 18 patients who clinically had local recurrence, 17 were salvaged by a secondary treatment. There were no complications requiring medical or surgical attention. A tendency toward increasing local control rates with increasing total doses was observed in the range between 57.5 Gy and 72.5. No significant correlation was found between local control rates and field size, daily dose, or the technique used. A tendency toward a lower local control rate was noted for patients whose anterior commissures were grossly involved; however, it is not known if this could be attributed to the use of 6 MeV X rays. The results are comparable to those obtained with 60Co as reported in the literature. It is concluded that 6 MeV X rays on a free set-up delivering 65-70 Gy in 6 1/2-7 weeks can be used satisfactorily for the treatment of early glottic carcinoma.