What is the recommended dosing for Y90 (Yttrium-90) radioembolization?

Y90 Radioembolization Dosing Recommendations

For optimal outcomes in Y90 radioembolization, personalized dosimetry with tumor-absorbed doses of at least 205 Gy should be delivered to the tumor, which significantly improves survival compared to standard dosing approaches. 1

Dosing Approaches and Considerations

Standard vs. Personalized Dosimetry

• Standard dosing approach:

  • Traditional absorbed dose of 100-150 Gy to the perfused lobe 1
  • Associated with median survival of 10.7 months in BCLC stage B/C with tumors >7cm 1

• Personalized dosimetry approach:

  • Delivers at least 205 Gy to the tumor 1
  • Associated with median survival of 26.6 months (compared to 10.7 months with standard dosing) 1
  • Higher radiation doses (>150 Gy) have shown complete remission rates of 80-84% 1

Specific Dosing Techniques

1. Radiation Segmentectomy:

   • Delivers ablative doses >190 Gy to small segments containing early-stage HCC 2
   • Potential curative approach for early HCC

2. Radiation Lobectomy:

   • Used for large tumors requiring extended hepatectomy 2
   • Induces contralateral liver hypertrophy while treating the tumor
   • Allows for future surgical resection

3. Lobar Treatment:

   • Standard approach for multifocal disease within a lobe 2
   • Typically delivers 80-150 Gy to the target lobe

Pre-Treatment Assessment Requirements

1. Mandatory Workup:

   • Diagnostic angiography with technetium-99m macroaggregated albumin (MAA) scan 2
   • Lung shunt fraction calculation to prevent radiation pneumonitis 1
   • Assessment for potential extrahepatic microsphere deposition 2

2. Lung Dose Assessment:

   • Critical to prevent radiation pneumonitis 1
   • May be eliminated in patients with HCC within Milan criteria except those with transjugular intrahepatic portosystemic shunt 1

Patient Selection Factors Affecting Dosing

• Liver Function:

  • Child-Pugh score and bilirubin levels 2
  • For cirrhotic patients, more conservative approaches may be needed

• Tumor Characteristics:

  • Size: Higher doses (>150 Gy) for tumors ≥5 cm have shown 80% complete remission rates 1
  • Single vs. multifocal disease

• Risk Factors for Radioembolization-Induced Liver Disease (REILD):

  • Small liver (<1.5 L) 1
  • Small functional liver volume associated with cirrhosis 1
  • Systemic therapy within 2 months 1
  • Extensive infusion to both liver lobes 1
  • Tumor involvement >50% of the liver 1

Dose-Response Relationship

Recent evidence demonstrates a clear dose-response relationship in Y90 radioembolization:

• Responding tumors: mean absorbed dose of 170 Gy 3
• Stable disease: mean absorbed dose of 101 Gy 3
• Progressive disease: mean absorbed dose of 67 Gy 3

Based on this data, a minimum planned tumor-absorbed dose of 150 Gy is recommended 3

Implementation of Dosing

1. Computational Approaches:

   • Personalized dosimetry using computational fluid dynamics and Monte Carlo simulation can optimize dose distribution 4
   • Post-treatment PET imaging at 2 hours can verify dose distribution 4

2. Same-Day Protocol Option:

   • For select patients, planning angiography and treatment can be performed on the same day 5
   • Requires proper pre-procedure planning based on baseline imaging

Monitoring and Safety

• Monitor for REILD, which typically occurs 4-8 weeks post-treatment 1
• Delayed hepatotoxicity may occur up to 6 months after treatment 1
• Common side effects include temporary fatigue (most common), nausea, and abdominal pain 6

Conclusion

Y90 radioembolization dosing should be personalized based on tumor characteristics and liver function. The evidence strongly supports using higher doses (>205 Gy) to the tumor when feasible, as this significantly improves survival outcomes compared to standard dosing approaches. Proper pre-treatment assessment, including lung shunt calculation and careful patient selection, is essential to minimize complications while maximizing therapeutic efficacy.