Hydrodissection for SBRT in Tumors Abutting the Diaphragm

Technical Approach to Hydrodissection

• Hydrodissection can be used to safely create physical separation between tumors abutting the diaphragm and adjacent organs at risk, enabling delivery of ablative SBRT doses while meeting normal tissue constraints, as recommended by the National Comprehensive Cancer Network 1, 2

Clinical Evidence Supporting Safety and Efficacy

• The National Comprehensive Cancer Network recommends SBRT dosing of 30-50 Gy in 3-5 fractions for tumors abutting the diaphragm in the hepatobiliary region, with exact dose determined by ability to meet normal organ constraints and underlying liver function 1, 2
• Most tumors regardless of location may be amenable to SBRT if sufficient uninvolved liver exists and dose constraints can be respected, according to the National Comprehensive Cancer Network 1, 2
• Hydrodissection enables treatment of lesions that would otherwise be contraindicated due to proximity to critical structures including the diaphragm, as stated by the National Comprehensive Cancer Network 1, 2

Critical Planning Considerations

• Respiratory motion management is essential for diaphragm-adjacent tumors, and 4D-CT imaging should be used to capture full respiratory excursion of both tumor and diaphragm, as recommended by the Journal of Clinical Oncology 3, 4
• Verification that diaphragm dose constraints can be met after hydrodissection displacement is crucial, according to Praxis Medical Insights 2
• Strict adherence to liver radiation dose constraints is necessary, particularly for patients with Child-Pugh B cirrhosis who may require dose modifications, as recommended by the National Comprehensive Cancer Network 1, 2

Patient Selection Criteria

• The National Comprehensive Cancer Network recommends hydrodissection for lesions <5 cm where surgical resection is not possible 2
• Patients with Child-Pugh A liver function are the most appropriate candidates for hydrodissection, although carefully selected Child-Pugh B patients may also be considered, according to the National Comprehensive Cancer Network 1, 2
• Absolute contraindications for hydrodissection include Child-Pugh C cirrhosis and active coagulopathy or inability to safely place drainage catheter, as stated by the National Comprehensive Cancer Network 1, 2

Common Pitfalls to Avoid

• The National Comprehensive Cancer Network recommends ensuring multidisciplinary review confirms unresectability before committing to SBRT, as surgical resection remains preferred when feasible 1
• Praxis Medical Insights advises against attempting SBRT without adequate displacement verification at each treatment fraction, as displacement must be reproduced consistently 2
• Conventional low-dose palliative radiation should not be used when ablative SBRT with hydrodissection is feasible, as this achieves suboptimal local control, according to Praxis Medical Insights 2, 5