The purpose of this study was to assess the prognostic significance of the anterior commissure (AC) involvement in radiation therapy for T1-stage glottic squamous cell carcinoma.
Patients and methods: Sixty-four patients comprising 50 with AC negative tumor and 14 with AC positive tumor, were retrospectively analyzed. Irradiation was administered using parallel opposed lateral portals and wedge filters from 60 to 70 Gy with 2 Gy daily fraction. The tumor doses were estimated by a computer or by an ionization chamber and a thermoluminescence dosimeter.
Results: The 5-year local control rates of the AC negative and positive group were 89% and 58%, respectively. The actual dose on the AC was slightly lower than the expected dose which was calculated by a computer.
Conclusion: The AC involvement was one of poor prognostic factors. The under dosage which was caused by using wedge filters, might have had an effect on the local control.