Unresectable Colorectal Liver Metastases: Percutaneous Ablation Using CT-Guided High-Dose-Rate Brachytherapy (CT-HDBRT)

Purpose: To evaluate the clinical outcome of CT-guided high-dose-rate brachytherapy (CT-HDRBT) of unresectable colorectal liver metastases (CRLMs). Materials and Methods: Retrospective analysis of all consecutive patients with unresectable CRLMs treated with CT-HDRBT between January 2008 and November 2012. Treatment was performed by CT-guided catheter place-ment and high-dose-rate brachytherapy with an iridium-192 source. MRI follow-up was performed after 6 weeks and then every 3 months post-intervention. The primary endpoint was local tumor control (LTC); secondary endpoints included time to progression (TTP) and overall survival (OS). Results: 80 heavily pretreated patients with 179 metastases were available for MRI evaluation for a mean follow-up time of 16.9 months. The mean tumor diameter was 28.5 mm (range: 8 - 107 mm). No major complications were observed. A total of 23 (12.9 %) local tumor progressions were observed. Lesions >= 4 cm in diameter showed significantly more local progression than smaller lesions (< 4 cm). 50 patients (62.5 %) experienced systemic tumor progression. The median TTP was 6 months. 28 (43 %) patients died during the follow-up period. The median OS after ablation was 18 months. Conclusion: CT-HDRBT is an effective technique for the treatment of unresectable CRLMs and warrants promising LTC rates compared to thermal ablative techniques. A combination with other local and systemic therapies should be evaluated in patients with lesions >4 cm in diameter, in which higher progression rates are expected.