Optimal time-dose relationships in high dose-rate intracavitary irradiation for carcinoma of the cervix uteri using time, dose and fractionation values

Abstract

Optimal time-dose relationships using the time, dose and fractionation (TDF) concept in high dose-rate intracavitary irradiation of cervical cancer were studied in 30 patients. The intracavitary irradiation was performed with a remotely controlled afterloading system, equipped with sources of 1–2 Ci⁶⁰Co beads. Point ‘A' was given a mean total dose of 30 Gy with a fraction dose of 6 Gy per week. In addition a dose of 40–60 Gy was given to Point ‘B' by external irradiation at the rate of 2 Gy five times each week. Twenty-two of the 30 patients are alive without clinical evidence of recurrence or radiation injury. One patient has liver metastasis, six are dead and one has suffered from bleeding per rectum. Of the six who died, three had recurrence of cancer, two died of other causes and one had a perforation of the ileum. Of the three patients with recurrence, two had recurrence in the parametrium, one at the cervix. The TDF value of the patient with perforation of the ileum was 187, that of the patient with bleeding per rectum 165 and that of the patient with the local recurrence in the cervix 106. The mean TDF value of 11 survivors in Stages I and II was 110 ± 9.5, and that of 12 survivors in Stages III and IV was 142 ± 12. In all stages the mean TDF value of the 22 survivors without clinical evidence of recurrence or radiation injury was 126 ± 10. It is concluded that the optimal time-dose relationship is a TDF of 126 ± 10, and a TDF of 160 or more should not be given, regardless of the stage, in order to keep radiation injury as low as possible.