Prognostic factors and outcomes of CT-guided Iodine-125 seed brachytherapy for retroperitoneal lymph node metastases from a previously irradiated field in cervical carcinoma: a multicenter retrospective study.

OBJECTIVE: This retrospective study aimed to evaluate the efficacy, safety, and prognostic factors of Iodine-125 seed brachytherapy for Retroperitoneal Lymph Node Metastases (RLNM) from a Previously Irradiated Field in Cervical Carcinoma. METHODS: Between March 2020 and November 2024, 33 patients (40 lesions) with RLNM from Cervical Carcinoma, who were ineligible for or declined further external beam radiotherapy (EBRT), underwent CT-guided iodine-125 seed brachytherapy at three tertiary hospitals. The follow-up deadline was 28/02/2026. The following endpoints were assessed: disease control rate (DCR), local tumor progression-free survival (LTPFS), overall survival (OS), and adverse events. RESULTS: The median follow-up time was 18.6 months (range, 2.0-38.3 months), and the 3- and 6- month DCR was 90.0% and 77.5%, respectively. The median LTPFS was 9.0 months (IQR, 5.3 - 20.5), and the median OS was 20.0 months (IQR, 8.0 - 25.0). The 6-, 12-, 18- and 24- month survival rates were 81.8%, 60.5%, 50.2%, 28.2%, respectively. Among 8 patients with preoperative pain, the Numerical Rating Scale (NRS) score decreased from 3.50 ± 1.77 to 1.75 ± 1.49 one month postoperatively (t=3.564, P = 0.009), a statistically significant difference. One patient developed a sigmoid colon fistula 4 months postoperatively. Four patients experienced postoperative low back discomfort with NRS scores of 1-2, which was relieved spontaneously or with oral analgesics. Multivariate analysis using the Cox proportional hazards model showed that a dose to 90% of the gross tumor volume (D90) ≥ 108 Gy was a protective factor for LTPFS, and tumor invasion of the intestinal wall was a risk factor for OS. CONCLUSION: Iodine-125 seed brachytherapy is safe and effective for treating RLNM in Cervical Carcinoma. A D90 ≥ 108 Gy results in better LTPFS. Tumor invasion of the intestinal wall is a risk factor for OS.