What are the indications and treatment regimen for the Y90 (Yttrium-90) procedure in patients with liver cancer?

Indications and Treatment Regimen for Y90 Radioembolization in Liver Cancer

Yttrium-90 (Y90) radioembolization is indicated for unresectable hepatocellular carcinoma (HCC) with preserved liver function, and offers superior time to progression compared to transarterial chemoembolization, particularly for solitary tumors and those ≥5 cm in size. 1

Primary Indications for Y90 Radioembolization

Y90 radioembolization delivers radioactive microspheres directly to liver tumors via the hepatic artery, sparing healthy liver tissue which receives most of its blood supply from the portal vein 2. The main indications include:

1. Unresectable HCC with liver-confined disease:

   • Solitary unresectable HCC (particularly ≥5 cm) 1, 3
   • Early-stage HCC not amenable to radiofrequency ablation 1
   • HCC with preserved liver function where TACE or systemic therapy is not feasible 4

2. Bridge to liver transplantation or resection:

   • Downstaging tumors to meet transplantation criteria 1, 2
   • Radiation lobectomy to induce contralateral liver hypertrophy before resection 1

3. HCC with portal vein thrombosis due to tumor invasion 2

4. Palliative treatment for advanced HCC with liver-confined disease 2, 5

Treatment Approaches and Regimens

1. Pre-treatment Assessment

• Mandatory workup:
  • Diagnostic angiography with technetium-99m macroaggregated albumin (MAA) scan
  • Lung shunt fraction calculation
  • Assessment for potential extrahepatic microsphere deposition 1, 2

2. Treatment Delivery Options

• Radiation Segmentectomy:

  • Delivers ablative radiation doses (>190 Gy) to small segments containing early-stage HCC
  • Potential curative approach for early HCC 1, 5
  • Particularly effective for solitary tumors not amenable to ablation 1

• Radiation Lobectomy:

  • Used for large tumors requiring extended hepatectomy
  • Induces contralateral liver hypertrophy while treating the tumor
  • Allows for future surgical resection 1, 6

• Lobar Treatment:

  • Standard approach for multifocal disease within a lobe
  • Typically delivers 80-150 Gy to the target lobe 1

3. Available Y90 Devices

Two main types of microspheres are available:

• TheraSphere® (glass microspheres)
• SIR-Spheres® (resin microspheres) 2

Both are administered on an outpatient basis, with dosing personalized based on tumor burden, liver function, and patient characteristics 1, 2, 3.

Comparative Effectiveness

Y90 radioembolization offers several advantages compared to other locoregional therapies:

• Superior time to progression compared to transarterial chemoembolization (TACE) 1
• Better outcomes for large tumors (≥5 cm) compared to TACE 1, 5
• Effective option for patients with portal vein thrombosis where TACE is contraindicated 2
• Single treatment session versus multiple sessions for TACE 3

A network meta-analysis of survival data comparing radiofrequency ablation, radiation therapy, TACE, and Y90 showed Y90 to be an effective treatment option with favorable survival outcomes 1.

Patient Selection Considerations

The most recent guidelines emphasize careful patient selection based on:

1. Tumor characteristics:

   • Size, number, and location of lesions
   • Presence of vascular invasion

2. Liver function:

   • Child-Pugh score (ideally A or early B)
   • Bilirubin levels (<2 mg/dL preferred)

3. Patient performance status:

   • ECOG 0-2 generally preferred 1, 5

Potential Complications and Management

Complications are relatively uncommon but may include:

• Post-embolization syndrome: Nausea, fatigue, abdominal pain (most common)
• Hepatic dysfunction: Monitor liver function tests post-procedure
• Radiation pneumonitis: Rare if lung shunt fraction is properly assessed
• GI ulceration: Can occur with inadvertent deposition in GI tract
• Radiation-induced liver disease: More common with compromised baseline liver function 1, 2

Important Caveats

• Proper dosimetry is critical - The most recent 2022 recommendations from an international multidisciplinary working group emphasize personalized dosing based on tumor characteristics and liver function 1

• Timing of surgery after Y90 - If downstaging to resection is planned, the median time from Y90 to surgery is approximately 9.5 months, with significant perioperative challenges 6

• Patient follow-up - Response assessment should include both anatomic and functional imaging, as tumor necrosis may not correlate with size reduction 1, 3