Selective Radioembolization Yields Improved Outcomes in Hepatocellular Carcinoma
In This Article
- The technique known as radioembolization takes advantage of the dual supply of blood in liver cancer to target the tumor cells while sparing healthy tissue
- Historically, physicians have used radioembolization to treat either a single lobe or the entire liver
- An emerging technique, selective radioembolization can allow treatment of the tumor-bearing portion of the liver only, enabling delivery of higher doses of radiation
- Researchers describe the benefits of selective radioembolization and explore its use in the clinic
Traditionally, radioembolization (also known as TARE/SIRT/Y90) has been used to treat either a single liver lobe or the entire liver in patients with intermediate or advanced hepatocellular carcinoma (HCC) as well as in patients with multifocal hepatic metastases. In recent years, though, physicians have been exploring another possible application of the technique—selective radioembolization of the tumor-bearing portion of the liver—which allows for the delivery of higher doses of radiation while preserving the healthy portion.
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"Instead of delivering radiation throughout a liver lobe, we are delivering an ablative dose to the site of concern," said Eric Wehrenberg-Klee, MD, an interventional radiologist in the Department of Radiology at Massachusetts General Hospital, who is working to advance selective radioembolization for clinical use. "We can maximize the therapeutic effect while minimizing hepatic toxicity."
Importantly, this means that the technique can now also be used as definitive treatment for patients with solitary HCC lesions, who often have limited options otherwise when seeking curative treatment.
90Y Beads Facilitate Segmental Treatment of the Liver
Radioembolization is a minimally invasive technique in which glass or resin microspheres incorporating the radioactive isotope yttrium-90 (90Y) are introduced into an artery leading to the liver, ultimately both blocking the further supply of blood to the tumor—the embolization part of the name—and delivering a dose of radiation to kill cancer cells.
The technique takes advantage of the dual supply of blood in liver cancer. Cancer cells are generally supplied by arterial blood, while normal tissue is generally supplied by portal venous blood. Thus, by delivering the 90Y beads through an artery, radioembolization specifically targets tumor cells while sparing the normal tissue.
Recent refinements in the technique have enabled selective, segmental treatment of the liver—as opposed to the more widely known strategy of lobar infusion. This allows delivery of higher doses and thus greater precision in removing tumors from the liver without having to perform open surgery.
A move toward segmental and even more selective treatment translates to improved response rates in patients with HCC.
Study Demonstrates Higher Response Rates With the Emerging Technique
In a retrospective, multicenter study published in Hepatology in November 2021, a team of investigators at Northwestern Feinberg School of Medicine, the University of California Los Angeles Medical Center, and elsewhere assessed both the response rates and the duration of response in patients with unresectable, solitary HCC who had undergone treatment with 90Y glass beads delivering high doses of radiation to the tumor.
The study confirmed the clinical benefit of radioembolization with 90Y microspheres. Based on the outcomes of the 162 patients included in the study, the researchers reported an objective response rate of 88.3%, with 62.2% of the patients showing the durability of response of six months or greater. The overall survival rate at three years was 86.6% for all patients included in the study and 92.8% for the subset of patients for whom radioembolization was performed as neoadjuvant therapy for transplantation or resection.
The study's authors also explored the relationship between radiation dose and outcomes. After discussing findings both from their own analysis and from previous work by other researchers, they emphasized personalized and optimized dosimetry as the next important area of investigation in the advancement of radioembolization for the treatment of HCC.
Based on the findings of the Hepatology study, the US Food and Drug Administration (FDA) has granted approval for use of the beads clinically.
Better Understandings of Likelihood of Response Will Inform Treatment Decisions
Mass General is currently participating in a multi-center study evaluating just this type of personalized dosimetry for HCC treatment. The study, titled the DOORwaY90 study, is evaluating resin Y90 beads with the use of partition dosimetry. Following treatment, patients will also be imaged with SPECT/CT or PET/CT imaging to enable visualization of their treatment and calculate the actual dose the tumor received. This advanced post-treatment imaging will allow physicians and patients to immediately understand the treatment response likelihood and plan the next steps.
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