Radiation therapy for early glottic carcinoma (T1N0M0). The final results of prospective randomized study concerning radiation field.

PURPOSE: To investigate the effect of radiation field on the local control of early glottic carcinoma by prospective randomized study. PATIENTS AND METHODS: From May 1982 through February 1992, a total of 273 patients with early glottic carcinoma (T1N0M0) was treated at our department with a wedge filter technique using a shell to improve the dose distribution and immobilization during radiotherapy with 4 MV X-ray. Patients were randomly allocated to either treatment group A (radiation field size: 5 x 5 cm) or B (6 x 6 cm) using bilateral parallel opposed portals. Total radiation dose administered was 60 Gy in 30 fractions over a 6-week period.
RESULTS: The 5-year recurrence-free survival rates were 88% in groups A and B (no significant difference). Minor chronic complication such as persistent arytenoid edema lasting more than 6 months or benign polypoid lesion of vocal cord was more frequently observed in group B (23%) than in group A (17%) (p = 0.038) while acute mucosal reaction and skin reaction showed no significant differences.
CONCLUSION: A small field (5 x 5 cm) with an appropriate angle of wedge filter and shell fixing device is recommended to avoid adverse effect with keeping local control of early glottic carcinoma.

RCT Entities:   Population Interventions Outcomes