Overall time in telecobalt therapy for T1 glottic carcinoma treated with 2 Gy per day

We already reported the tumor response during radiotherapy as a prognostic factor for T1 glottic carcinoma. In these reports, we did not evaluate the overall treatment time. There were many reports of correlation between local control and overall treatment time of radiation for head and neck cancer. Our aim was to evaluate the overall treatment time as a prognostic factor of the local control for T1 glottic carcinoma or not.

From 1967 through 1985, 295 patients of T1 glottic carcinoma were treated with telecobalt therapy at the Department of Radiology, Osaka University Medical School. Of 295 patients, 219 patients treated with 2 Gy per day were evaluated. The median of total doses was 60 Gy (42 to 72 Gy). Overall treatment times of patients with tumor clearance at 40 Gy were significantly shorter than those with tumor persistence at 40 Gy.

According to the univariate analysis, there were no statistically significant factors for local control except tumor response during treatment. Of 124 patients treated with a total dose of 60 Gy and the overall treatment time of 40 to 46 days, local control rates of patients treated with the overall treatment time of 40 to 42 days and 43 to 46 days were 88% and 78%, respectively (p = 0.3072). For 91 patients with tumor clearance at 40 Gy, local control rates of patients treated with the overall treatment time of 40 to 42 days and 43 to 46 days were 96% and 82%, respectively (p = 0.1645). Corresponding figures for 31 patients with tumor persistence at 40 Gy were 63% and 65%, respectively (p = 0.4227).

We compare the treatment results of patients treated with the same total dose and the same tumor response during radiotherapy. We concluded that the overall treatment time was not a prognostic factor for T1 glottic tumor treated with overall time of 40 to 46 days.