Evaluation of late morbidity in patients with carcinoma of the uterine cervix following a dose rate change

Background: A retrospective analysis of late complications for patients with cervical cancer treated with two different brachytherapy schedules in one institute, using the French-Italian glossary. Materials and methods: From 1979 until 1986, a total of 77 patients were treated with external radiation followed by two intracavitary applications with the Gynatron Cs-137 afterloading (dose rate 0. 54 Gy/h). After 1986, 66 patients received intracavitary applications with Selectron-LDR (dose rate 1.07 Gy/h). Because of the expected increase in complications with increasing dose rate, the dose per application was reduced from 25 Gy to 20 Gy. Results: 49/77 late gastrointestinal and urinary complications were scored in the Gynatron group and 46/68 in the Selectron group. Actuarial estimates at 5 years showed 42% and 54.1% late gastrointestinal complications and 16.9% and 24.1% for late urinary complications in the patients treated with, respectively, the Gynatron and Selectron. Conclusions: Despite the dose reduction, there remains a clear dose rate influence on the late morbidity. Correction for this influence is essential