Radiation therapy for early glottic carcinoma: indication for the wedge filter.

From 1977 to the end of 1987, 244 patients with early glottic carcinoma (T1N0M0) were treated with radiation therapy. For 95 patients (group A), a styrofoam head holder and band were used to ensure immobilization during treatment without a wedge filter and for 149 patients (group B) a shell fixing devise and wedge filter were used. Total radiation dose administered was 50 to 70 Gy over a period of five to seven weeks with fields of 5 x 5 cm (group A) and 5 x 5 cm (group B1: n = 74) or 6 x 6 cm (group B2: n = 75). The five-year relapse-free survival (RFS) rates for group A and B were 85% and 90%, respectively, and RFS was essentially the same (p = 0.241). In group B, RFS was also basically the same for groups B1 and B2 (p = 0.78). According to tumor size, however, in patients with large T1a lesions (total length of one vocal cord) five-year RFS rates for groups A and B were 62% and 88%, respectively, and RFS was statistically significantly different (p = 0.003). Up to five years, seven patients (9%) of group A and 23 patients (17%) of group B showed minor chronic complication. As a minor chronic complication, arytenoid edema was found more frequently in group B (n = 15) than group A (n = 0). Eleven of these 15 cases were treated with large field (6 x 6 cm). For large T1a lesions of glottic carcinoma, a wedge filter was useful. A small field (5 x 5 cm) with an appropriate angle of wedge filter is recommended to avoid late arytenoid edema and achieve a more homogeneous dose distribution.