Safety and efficacy of iridium-192 high-dose-rate interstitial brachytherapy for pleural and chest wall tumours: preliminary results

Purpose
To evaluate the safety and efficacy of computed tomography (CT)-guided iridium-192 (¹⁹²Ir) high-dose-rate (HDR) interstitial brachytherapy (ISBT) for pleural and chest wall malignant tumours.

Material and methods:
This single-centre retrospective cohort study involved 21 patients with pleural/chest wall malignant tumours treated between January 2024 and January 2025. All patients underwent HDR ISBT (30 Gy in a single fraction). Treatment included CT-guided needle implantation, three-dimensional dose optimisation (Oncentra system), and adherence to Radiation Therapy Oncology Group dose constraints for organs at risk (OARs). Efficacy endpoints included objective response (Response Evaluation Criteria in Solid Tumours v1.1), pain relief (Numerical Rating Scale), and dosimetric comparison with virtual stereotactic body radiotherapy. Safety was assessed using the Radiation Therapy Oncology Group/European Organisation for Research and Treatment of Cancer toxicity criteria.

Results:
The median follow-up duration was 7.48 months. The objective response rate (complete response + partial response) was 76.19%, with 28.57% achieving a complete response and 47.62% achieving a partial response. Pain relief was achieved in 87.5% of patients with pretreatment pain, with numerical rating scale scores decreasing from moderate to severe (median, 6) to mild (median, 3) at 1 month. No ≥ grade II complications (e.g. bronchopleural fistula, pneumothorax) occurred; only four patients experienced minor subcutaneous haemorrhage/emphysema. Dosimetric analysis showed a significantly higher target mean dose with ISBT than with stereotactic body radiotherapy (p < 0.001), while OARs doses (e.g. lungs, heart, spinal cord) remained within Radiation Therapy Oncology Group limits. Rib and chest wall dose exceedances were rare and clinically insignificant.

Conclusions:
Computed tomography-guided 192Ir HDR ISBT offers safe, effective local control and rapid pain relief for pleural/chest wall tumours, demonstrating superior dosimetric conformity and lower toxicity to OARs. This minimally invasive approach is a viable option for patients unsuitable for surgery or external beam radiotherapy.