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.