[Update on interstitial brachytherapy].

CLINICAL/METHODICAL ISSUE: Minimally invasive treatment procedures, such as image-guided local tumour ablation have gained increasing relevance in oncologic concepts. Limitations of thermal ablation procedures have led to the development of percutaneous, computed tomography (CT) guided brachytherapy. STANDARD RADIOLOGICAL
METHODS: Thermal ablation procedures, such as radiofrequency ablation (RFA) and laser-induced thermotherapy (LITT) show limitations regarding maximum tumour size (<5 cm), cooling effects of adjacent vessels and surrounding risk structures. METHODICAL INNOVATIONS: The image-guided interstitial brachytherapy allows the single application of high-dose rate (HDR) irradiation with an extensive protracted cytotoxic effect. Adjacent risk structures play a minor role due to the steep dose gradient outside the clinical target volume. PERFORMANCE: Studies using CT-guided brachytherapy resulted in a local tumour control rate of approximately 90% after 12 months in the treatment of hepatocellular carcinoma (HCC) and 70-90% in the treatment of colorectal metastases or cholangiocellular carcinoma (CCC). Similar response rates were also seen in the treatment of metastases of renal cell carcinoma (RCC), non-small cell lung cancer (NSCLC) or neuroendocrine tumours. In colorectal liver metastases and HCC the method has proven to have a positive impact on prognosis. ACHIEVEMENTS: In contrast to thermal ablation the method can be used without restriction with respect to tumour location. Cooling effects do not play a role. It has already been applied in more than 5,000 cases and it is used in clinical routine. PRACTICAL RECOMMENDATIONS: Image-guided brachytherapy is safe and effective and has found its way into the clinical routine.