Image-guided interstitial high-dose-rate brachytherapy in the treatment of metastatic esophageal squamous cell carcinoma

Purpose: To evaluate the efficacy of computed tomography (CT)- and magnetic resonance imaging (MRI)-guided interstitial high-dose-rate brachytherapy (HDR IBT = IBT) in patients with metastatic esophageal squamous cell carcinoma. Material and methods: Eleven patients with 21 unresectable metastases of histologically proven esophageal squamous cell carcinoma were included in this retrospective study. Fourteen visceral and 7 lung metastases were treated with image-guided (CT or open MRI guidance) IBT using a 192 lridium source (single fraction irradiation). Clinical and imaging follow-up were performed every 3 months after treatment. Primary endpoint was local tumor control (LTC) and safety. Furthermore, we analyzed safety, progression-free survival (PFS), and overall survival (OS). Results: The median diameter of the target lesions was 2.2 cm (range: 0.7-6.8 cm), treated with a median D-100 of 20.1 Gy (range: 10-25 Gy). During a median follow-up of 6.3 months (range: 3-21.8 months), three patients displayed local recurrences, resulting in LTC of 85.7%. Median PFS was 3.4 months and median OS after IBT was 13.7 months. No severe adverse events (grade 3+) requiring hospitalization or invasive intervention were recorded. Conclusions: Image-guided IBT is a safe and effective treatment in patients with metastasized esophageal squamous cell carcinoma.