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

Abstract

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. 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 3-5days before brachytherapy; dosimetry verification was performed immediately after brachytherapy. The actuarial D90 (dose delivered to 90% of the target volume) was 100-198Gy (median, 126.5Gy). In 9 patients, pain intensity decreased to mild pain 1-3weeks after brachytherapy. Pain-free survival ranged 2-15months (median, 5months; 95% confidence interval [CI]: 0.1, 9.9). The overall response rate was 19 of 19 (100%). The median local control time was 15months (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 10months (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. 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.