High versus low dose-rate intracavitary radiotherapy in the treatment of carcinoma of the uterus

This study comprised a material of 401 patients with St. I-II cervical or endometrial carcinoma. From 1969 to 1976, 101 patients with St. Ia-IIb cervical carcinoma were treated with intracavitary high dose-rate afterloading Co60 irradiation using the Cathetron (C) and 84 patients with low dose-rate irradiation using radium (R). From 1970-1976, 91 patients with St.I-II endometrial carcinoma were treated with the Cathetron and 125 with radium. There were no statistically significant differences in the survival rates between the two treatment groups. During the first 2 years of C treatment, the treatments were given in fractions of 10 Gy each, but were then lowered to 7.5 Gy each for the last 5 years. The rates of complications decreased from 42.4 to 20.6 per cent in cervical carcinoma and from 33.3 to 11.4 per cent in endometrial carcinoma. When only the last 5 years of C treatment are considered, there were no statistical differences between the C and R groups. A new normalizing constant of 1.18 for the TDF equation to replace the recommended 1.57 was proposed. In the light of the present study and earlier reports from other centres it can be concluded that radium can safely replaced by afterloading high dose-rate Co60 (Cathetron) without lowering the survival rates or increasing the rate of complications with the doses currently used in the treatment of St. I-II cervical carcinoma and St. I-II endometrial carcinoma associated with a small uterine cavity. There is, however, a need for designing new catheter and source selections to better facilitate the treatment of endometrial carcinoma associated with a large uterine cavity. (Author)