Prognostic factor of telecobalt therapy for early glottic carcinoma.

Abstract

Local control rates of T1 and T2 glottic carcinoma treated with radiation alone were reported as 80-91% and 63-76%, respectively. The authors investigated the factors that affect the local control rate for early glottic carcinoma. From 1967 through 1982, 330 patients with early glottic carcinoma (T1: 274 patients; T2: 56) were treated with telecobalt therapy at the Department of Radiology, Osaka University Hospital, Osaka, Japan. Five-year actuarial survival rates of patients with T1 and T2 were 79% and 80%, respectively. Five-year local disease control rates of patients with T1 and T2 disease were 81% and 67%, respectively. In 243 of 254 patients treated with 2 Gy a day, tumor response could be evaluated at the dose level of 40 Gy. For tumors treated with a daily dose of 2 Gy, local control rates of 153 tumors that disappeared at 40 Gy and 90 tumors that persisted at 40 Gy were 83% and 62%, respectively (P < 0.001). Field size and daily fraction size did not affect the local control rate. Evaluation of tumor response at 40 Gy was an important indicator of local disease control for early glottic cancers treated with 2 Gy a day.