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Zach Berman MD

Y90XX.Radiation Segmentectomy HCC

Radiation Segmentectomy: A Focused Approach to Liver Tumor Management

Radiation segmentectomy is a specialized form of transarterial radioembolization (TARE) that targets small, well-defined liver lesions, primarily in hepatocellular carcinoma (HCC) and metastatic liver disease. This technique leverages the precision of delivering high-dose radiation to a specific liver segment, allowing for a minimally invasive yet curative-intent treatment option in select patients. Below, we summarize the principles, methodology, and key studies that have shaped the understanding and application of radiation segmentectomy.

Principles and Methodology

Radiation segmentectomy is designed to treat lesions localized to one or two liver segments by delivering targeted radiation using yttrium-90 (¹¹⁹Y) microspheres. The goal is to achieve tumor ablation through localized high-dose radiation while preserving the surrounding liver parenchyma.

Key procedural steps include:

  1. Patient Selection: Ideal candidates are those with limited disease burden (e.g., solitary tumors or oligonodular disease within one or two liver segments) and preserved liver function (Child-Pugh A or early B).
  2. Angiographic Mapping: Pre-procedure angiography delineates the hepatic arterial anatomy, identifies potential non-target areas, and facilitates catheter placement.
  3. Dose Planning: High radiation doses (e.g., >190 Gy to the target segment) are calculated to maximize tumoricidal effects while minimizing systemic exposure.
  4. Delivery: ¹¹⁹Y microspheres are infused into the hepatic artery branches supplying the target segment, with the aim of achieving selective radiation.

Key Studies and Outcomes

1. Rationale and Initial Validation: Kennedy et al. (2009) introduced the concept of radiation segmentectomy, emphasizing its potential as a curative approach for HCC patients who are not surgical candidates. The study highlighted high rates of complete necrosis in treated tumors and excellent local control, with minimal liver toxicity.

2. LEGACY Study (2021): The LEGACY trial provided robust data on the efficacy of radiation segmentectomy in early-stage HCC. This retrospective, multicenter study evaluated outcomes in patients undergoing radiation segmentectomy with ¹¹⁹Y glass microspheres. Key findings included:

  • Objective Response Rate (ORR): 84% (per mRECIST criteria).
  • Pathologic Complete Response (pCR): Achieved in 70% of explanted livers.
  • Median Overall Survival (OS): Not reached; estimated 3-year OS was 86%.
  • Durable Local Control: Sustained control in treated segments with low recurrence rates.

These outcomes positioned radiation segmentectomy as a potential alternative to surgical resection in select patients.

3. DOSISPHERE-01 (2021): Although primarily focused on dose escalation in TARE, DOSISPHERE-01 underscored the importance of high-dose delivery in achieving superior outcomes. The study’s findings supported the segmentectomy approach by demonstrating improved tumor response with doses exceeding 205 Gy, a hallmark of radiation segmentectomy planning.

4. Comparative Studies with Ablation: Recent studies have compared radiation segmentectomy with thermal ablation (e.g., microwave or radiofrequency ablation) for small HCC lesions. While both approaches showed high efficacy, radiation segmentectomy was advantageous for lesions near critical structures or larger tumors (>3 cm), where ablation risks incomplete treatment or collateral damage.

5. Real-World Evidence: Several real-world studies have corroborated clinical trial findings, highlighting the feasibility and safety of radiation segmentectomy across diverse patient populations. Consistently, these studies report:

  • High local tumor control rates (~90%).
  • Preservation of liver function with low rates of post-procedure hepatic decompensation.
  • Extended progression-free survival (PFS) in non-surgical candidates.

Clinical Implications

Radiation segmentectomy represents a paradigm shift in liver-directed therapies, bridging the gap between palliative embolization and curative surgical options. Its advantages include:

  • Precision: High-dose, localized radiation minimizes collateral damage.
  • Curative Potential: For early-stage HCC and select metastatic lesions, it offers outcomes comparable to surgery or ablation.
  • Expanded Eligibility: Suitable for patients with contraindications to resection or ablation.

Limitations and Future Directions

Despite its promise, radiation segmentectomy is not without challenges:

  • Technical Expertise: Requires advanced interventional radiology skills and meticulous planning.
  • Radiation Safety: Demands stringent protocols to prevent non-target embolization.
  • Cost and Accessibility: The procedure’s complexity and resource requirements may limit widespread adoption.

Future research aims to:

  • Refine patient selection criteria using imaging and biomarkers.
  • Explore combination therapies (e.g., immunotherapy and TARE).
  • Validate its role in non-HCC liver tumors.

Conclusion

Radiation segmentectomy has emerged as a powerful tool in the armamentarium against liver tumors, offering a minimally invasive, yet highly effective, treatment for select patients. Through continued innovation and rigorous clinical evaluation, this technique holds the potential to redefine standards of care in interventional oncology.