Background: 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.
Methods: 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.
Results: 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.
Conclusion: 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.