28 Primary and secondary liver malignancies

Primary and secondary liver malignancies

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THE GEC ESTROHANDBOOKOF BRACHYTHERAPY | Part II Clinical Practice Version 1 - 15/07/2022

28 Primary and secondary liver malignancies

Stefanie Corradini, Lukas Nierer, Maya Rottler, Franziska Walter, Konrad Mohnike, Marc Mühlmann, Max Seidensticker, Jens Ricke, Peter Hass

1. Summary 2. Introduction 3. Anatomy 4. Pathology

3 3 3 5 5 6 7 8

9. Treatment planning

9

10. Dose, dose rate and fractionation

10 11 12 14 14 15

11. Monitoring

12. Results

5. Work up

13. Adverse side effects 14. Key messages

6. Indications, contra-indications 7. Tumour and target volumes

15. References

8. Technique

1. SUMMARY

With interstitial HDR liver brachytherapy, excellent local control rates of >90% at 12 months can be achieved for various entities with prescription doses of 15-25 Gy (depending on histology) in a single session. In contrast to stereotactic body radiation therapy (SBRT), liver brachytherapy allows the application of higher doses to the tumour while sparing surrounding organs at risk. Unlike thermal procedures, tumour size is not a limitation with brachytherapy, nor is central location (heat sink effect). Moreover, exposure of adjacent organs at risk can be determined during treatment planning, and dose constraints for OARs can be met to avoid normal tissue toxicities. Therefore, the available evidence suggests that this minimally invasive treatment option is particularly beneficial in the treatment of large liver tumours, multiple lesions, or tumours in central location.

2. INTRODUCTION

placement. In the hands of experienced radiation oncologists or interventional radiologists, toxicity rates and serious procedural complications (major bleeding or infection after the procedure) are very limited [3].

High-dose rate interstitial brachytherapy (HDR brachytherapy) is a treatment option with high local control rates for primary liver malignancies, such as hepatocellular carcinoma (HCC) or cholangiocarcinoma (CCC), and for secondary liver malignancies in oligometastatic disease. HDR brachytherapy is performed using the afterloading technique and high dose rate radioactive sources containing β- or γ-emitting radioisotopes such as iridium-192, which allows short irradiation times of about 10minutes for small lesions to 90 minutes for large lesions [1]. With this technique, very high doses can be applied to liver lesions while optimally sparing healthy liver tissue and adjacent organs at risk (OAR) due to the inherent steep radiation dose gradient. The steep dose gradient is mainly achieved due to the geometric conditions (small source; decrease of radiation fluence by square of distance) and to some minor extent due to attenuation in the tissue. Recent analyses comparing HDR brachytherapy with virtually planned stereotactic body radiotherapy for ablative treatment of liver malignancies showed superiority of HDR brachytherapy in terms of dose coverage of the target volume and liver volume irradiated to 5 Gy [2]. For optimal HDR brachytherapy of the liver, close collaboration between radiation oncologists, medical physicists, and interventional radiologists is required. First, brachytherapy catheters are placed under image guidance (usually computed tomography). Achievable dose coverage of the target depends largely on the catheter

3. ANATOMY

Procedure planning, catheter placement, target delineation and dose optimization require in-depth knowledge of general and patient specific anatomy and anatomic relationships between target lesions and organs at risk. In general, the Couinaud classification divides the liver into 8 segments with further subdivision of segment 4 in 4a and 4b (see figure 1) [5,6]. Liver segments 5-8 are in the right liver lobe, liver segments 2-4 are in the left liver lobe. Each segment is functionally independent having main portal, arterial and biliary branches centrally as well as draining hepatic veins peripherally. The portal veins delineate the horizontal, the liver veins the vertical divisions between segments (segment 1 being the exception). CT and MRI are used in at least three steps to assess the required anatomic information i) before, ii) during and iii) after catheter placement. Preprocedural scans (step i) visualize general and patient specific anatomic features including congenital variations,