Role of Stereotactic Body Radiation Therapy in Unresectable Cholangiocarcinoma

Guideline-Based Recommendations

• The French Association for the Study of the Liver recommends that Stereotactic Body Radiation Therapy (SBRT) may be considered for unique intrahepatic cholangiocarcinoma lesions less than 5 cm if surgical resection is not possible, with an expert opinion and strong agreement 1, 2
• Conventional chemoradiotherapy is probably not recommended for patients with unresectable intrahepatic cholangiocarcinoma outside of therapeutic trial settings, with a GRADE 2− recommendation 1, 2, 3
• The French Association for the Study of the Liver suggests that SBRT may provide benefits including improved local control, overall survival, and acceptable toxicity in intrahepatic cholangiocarcinoma, based on several trials and meta-analyses 1, 2, 3
• Conventional chemoradiotherapy is probably not recommended for unresectable perihilar cholangiocarcinoma outside of clinical trials, with a GRADE 2− recommendation 1, 2
• Interventional radiology approaches are not recommended for perihilar cholangiocarcinoma, with a GRADE 1− recommendation 1, 2, 3

Patient Selection Criteria

• The French Association for the Study of the Liver recommends that solitary intrahepatic lesions less than 5 cm represent the best candidates for SBRT, based on guideline recommendations 1, 2
• Standard first-line systemic therapy remains cisplatin-gemcitabine with or without immunotherapy, as recommended by the French Association for the Study of the Liver 1

Role of SBRT in Locally Advanced Cholangiocarcinoma

Primary Treatment Indications

• The American College of Radiology recommends SBRT for hilar (perihilar) cholangiocarcinoma, demonstrating promising efficacy with 2-year local control rates of 47-78% 4

Clinical Outcomes Supporting SBRT Use

Combination Therapy

• The National Comprehensive Cancer Network suggests that SBRT should be combined with systemic chemotherapy, particularly gemcitabine plus cisplatin, which remains the standard first-line systemic therapy 4

Critical Pitfalls to Avoid

• The National Comprehensive Cancer Network advises against using SBRT for patients with Child-Pugh C cirrhosis, as safety has not been established in this population with very poor prognosis 5
• The American College of Radiology recommends avoiding conventional low-dose palliative radiation (8 Gy in 1 fraction) for cholangiocarcinoma, as this achieves suboptimal local control 4
• The National Comprehensive Cancer Network suggests ensuring lesions are not abutting critical structures (bile ducts, stomach, bowel) without appropriate planning, though hydrodissection techniques can enable safe treatment in some cases 5

Treatment Algorithm

• The National Comprehensive Cancer Network recommends confirming unresectability through multidisciplinary tumor board evaluation 5

SBRT for Cholangiocarcinoma Abutting the Diaphragm

Key Considerations for Diaphragm-Adjacent Lesions

• The National Comprehensive Cancer Network guidelines acknowledge that lesions abutting key structures such as the diaphragm may be difficult locations for ablation, but hydrodissection techniques can be used to safely treat in some instances, with careful consideration of normal tissue constraints in SBRT planning 6

Evidence Supporting SBRT Use in Cholangiocarcinoma

Guideline Recommendations

• The French Association for the Study of the Liver recommends SBRT for unique intrahepatic cholangiocarcinoma lesions less than 5 cm when surgical resection is not possible, with strong expert agreement 7
• Most tumors, irrespective of their location, may be amenable to SBRT, intensity-modulated radiation therapy, or conformal external beam radiation therapy, according to the National Comprehensive Cancer Network 6, 8

Dosing Recommendations

• SBRT dosing is typically 30-50 Gy in 3-5 fractions, depending on the ability to meet normal organ constraints and underlying liver function, as recommended by the National Comprehensive Cancer Network 6, 8

Critical Planning Considerations for Diaphragm-Adjacent Tumors

Technical Strategies

• Hydrodissection techniques can enable safe treatment of lesions abutting critical structures, including the diaphragm, as suggested by the National Comprehensive Cancer Network 6
• Ensure sufficient uninvolved liver volume and strict adherence to liver radiation dose constraints, as recommended by the National Comprehensive Cancer Network 6, 8

Patient Selection

• There is no strict size limit if sufficient uninvolved liver exists and dose constraints can be respected, according to the National Comprehensive Cancer Network 6, 8
• Most safety and efficacy data are available for patients with Child-Pugh A liver function; limited data exist for Child-Pugh B, as noted by the National Comprehensive Cancer Network 6, 8

Integration with Systemic Therapy

• The French Association for the Study of the Liver suggests that SBRT should be combined with systemic chemotherapy, particularly gemcitabine plus cisplatin, which remains the standard first-line systemic therapy 7
• First-line cisplatin-gemcitabine with durvalumab or pembrolizumab provides better overall survival than chemotherapy alone, according to the French Association for the Study of the Liver 7

Critical Pitfalls to Avoid

• Do not use SBRT for patients with Child-Pugh C cirrhosis, as safety has not been established in this population with very poor prognosis, as recommended by the National Comprehensive Cancer Network 6
• For lesions abutting the diaphragm specifically, verify that respiratory motion management is adequate and that diaphragm dose constraints can be met, as suggested by the National Comprehensive Cancer Network 6

SBRT Combined with Immunotherapy for Cholangiocarcinoma

Current Standard of Care Context

• The American College of Medical Oncology recommends first-line treatment for advanced cholangiocarcinoma as cisplatin-gemcitabine plus immunotherapy (durvalumab or pembrolizumab), which provides superior overall survival compared to chemotherapy alone, with a strength of evidence based on emerging data 9

Evidence for SBRT-Immunotherapy Combination

• The combination of SBRT and immunotherapy demonstrates acceptable safety profiles, with concurrent SBRT and immunotherapy not significantly increasing radiation necrosis rates compared to SBRT alone, based on data from brain metastases, suggesting acceptable safety for cholangiocarcinoma patients 10

Treatment Sequencing Algorithm

• The National Comprehensive Cancer Network suggests starting with cisplatin-gemcitabine plus durvalumab or pembrolizumab as standard first-line therapy, considering adding SBRT to oligometastatic sites during first-line immunotherapy-chemotherapy for patients with limited disease burden, based on the strength of evidence from clinical trials 9

Management of Acute Diaphragmatic Pleurisy Following Hepatic SBRT for Cholangiocarcinoma

Delayed Toxicities of Alternative Liver‑Directed Therapies

• Other liver‑directed treatments (e.g., radioembolization) are associated with delayed adverse events, such as radioembolization‑induced liver disease occurring 4–8 weeks after therapy and late hepatotoxicity manifesting beyond 6 months. 11

Imaging Evaluation for Persistent or Worsening Symptoms

• When pleuritic chest pain or related symptoms persist beyond 7–10 days after SBRT, a contrast‑enhanced CT scan of the thorax and abdomen should be obtained to rule out pleural effusion, radiation‑induced pneumonitis, or hepatic complications. 11