CT-guided permanent 125I seed interstitial brachytherapy for recurrent retroperitoneal lymph node metastases after external beam radiotherapy.

PURPOSE: To evaluate the feasibility, efficacy, and safety of permanent (125)I seed interstitial brachytherapy reirradiation in patients with retroperitoneal lymph node recurrence under CT guidance.

METHODS AND MATERIALS: Seventeen patients with 19 retroperitoneal lymph node recurrence after external beam radiotherapy underwent CT-guided (125)I seed implant brachytherapy from October 2007 to August 2014. Treatment for all patients was preplanned using a three-dimensional radiation therapy planning system 3-5 days before brachytherapy; dosimetry verification was performed immediately after brachytherapy.

RESULTS: The actuarial D90 (dose delivered to 90% of the target volume) was 100-198 Gy (median, 126.5 Gy). In 9 patients, pain intensity decreased to mild pain 1-3 weeks after brachytherapy. Pain-free survival ranged 2-15 months (median, 5 months; 95% confidence interval [CI]: 0.1, 9.9). The overall response rate was 19 of 19 (100%). The median local control time was 15 months (95% CI: 2.3, 27.7). The 6-, 12-, and 24-month local control rate was 88.0%, 63.2%, and 42.1%, respectively. Twelve patients (70.6%) developed distant metastases and died. Two patients (11.8%) are alive with distant metastases but no evidence of local recurrence. Three patients (17.6%) are alive with no evidence of local recurrence. Median overall survival was 10 months (95% CI: 5.7, 14.3); the 1- and 2-year survival rates were 38.1% and 15.3%, respectively. No major complications related to the procedure occurred during or after brachytherapy.

CONCLUSIONS: Reirradiation with CT-guided permanent (125)I seed interstitial brachytherapy is feasible, safe, and effective as pain relief or salvage treatment for patients with recurrent retroperitoneal lymph nodes.