Post-operative high dose rate brachytherapy in patients with low to intermediate risk endometrial cancer

Background and purpose: This paper investigates the outcome using different dose/fractionation schedules in high dose rate (HDR) post-operative vaginal vault radiotherapy in patients with low to intermediate risk endometrial cancer. Materials and methods: The world literature was reviewed and thirteen series were analyzed representing 1800 cases. Results: A total of 12 vaginal vault recurrences were identified representing an overall vaginal control rate of 99.3%. A wide range of dose fractionation schedules and techniques have been reported. In order to analyze a dose response relationship for tumor control and complications, the biologically effective doses to the tumor and late responding tissues were calculated using the linear quadratic model. A threshold was identified for complications, but not vaginal control. While dose fractionation schedules that delivered a biologically effective dose to the late responding tissues in excess of 100 Gy 3 (LQED=60 Gy) predicted for late complications, dose fractionation schedules that delivered a modest dose to the vaginal surface (50 Gy 10 or LQED=30 Gy) appeared tumoricidal with vaginal control rates of at least 98%. Conclusions: By using convenient, modest dose fractionation schedules, HDR vaginal vault – brachytherapy yields very high local control and extremely low morbidity rates.