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

Objective: To 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.

Methods: Twenty 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 2 Gy fractions (EQD2), assuming α/β = 10, for reirradiation was 48.8 Gy (range: 16.0-91.0 Gy), and the median cumulative EQD2 (for primary treatment and reirradiation) was 133.5 Gy (range: 96.8-164.2 Gy). The median follow-up after retreatment was 31 months (range: 6-86 months).

Results: The 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 2 cm(3) of rectum was 94.4 Gy (range: 67.1-118.8 Gy) and to 2 cm(3) of bladder was 99.3 Gy (range: 70.4-122.3 Gy). Grade 3 late toxicity was observed in 3 patients (15%). An interval between primary RT and reirradiation of ≤ 12 months and a tumor diameter >3 cm were significant prognostic factors adversely affecting OS, DFS and LC.

Conclusions: HDR BT is a valuable method for the reirradiation of cervical cancer. A cumulative EQD2 of approximately 100 Gy was safely delivered to 2 cm(3) of the bladder and the rectum.