HDR brachytherapy for the reirradiation of cervical and vaginal cancer: Analysis of efficacy and dosage delivered to organs at risk

Abstract

ObjectiveTo evaluate the efficacy and toxicity of HDR brachytherapy (BT) for the reirradiation of cervical or vaginal cancer arising within a previously irradiated area with a special focus on dosage delivery to organs at risk. MethodsTwenty consecutive patients with cervical (N=19) or vaginal (N=1) cancer were reirradiated with curative intent using BT with or without external beam irradiation and hyperthermia. The median biologically equivalent dose in 2Gy fractions (EQD2), assuming α/β=10, for reirradiation was 48.8Gy (range: 16.0–91.0Gy), and the median cumulative EQD2 (for primary treatment and reirradiation) was 133.5Gy (range: 96.8–164.2Gy). The median follow-up after retreatment was 31months (range: 6–86months). ResultsThe 3-year overall survival (OS) rate was 68% (95% confidence interval [CI]: 44%–91%). The 3-year disease-free survival (DFS) rate was 42% (95% CI: 19%–65%). The 3-year local control (LC) rate was 45% (95% CI: 22%–69%). For nine patients who received 3D treatment planning, the median cumulative EQD2 to 2cm3 of rectum was 94.4Gy (range: 67.1–118.8Gy) and to 2cm3 of bladder was 99.3Gy (range: 70.4–122.3Gy). Grade 3 late toxicity was observed in 3 patients (15%). An interval between primary RT and reirradiation of ≤12months and a tumor diameter >3cm were significant prognostic factors adversely affecting OS, DFS and LC. ConclusionsHDR BT is a valuable method for the reirradiation of cervical cancer. A cumulative EQD2 of approximately 100Gy was safely delivered to 2cm3 of the bladder and the rectum.