External beam radiation therapy can benefit patients with liver cancer awaiting transplantation, yet non-invasive radiation treatments are underutilized, researchers shared at the American Society for Radiation Oncology (ASTRO) Annual Meeting (Abstract 2078).
The first national analysis of external beam radiation as bridging therapy found fewer than 4 percent of patients are prescribed non-invasive external beam radiation treatment, said study author Nima Nabavizadeh, MD, Associate Professor of Radiation Oncology and Residency Program Director at Oregon Health & Science University in Portland.
He and his colleagues analyzed data from the United Network for Organ Sharing, a non-profit organization that operates the U.S. transplant system to see which bridging therapies were prescribed most often. They identified 18,447 hepatocellular carcinoma (HCC) patients who submitted Model of End-Stage Liver Disease exception applications during the study period.
Ultimately, 11,171 patients received a liver transplant (60.6%), with a medium waiting period of 7 months. In all, 15,759 (85.4%) patients received some liver-directed therapy (LDT). A total of 658 patients received external beam radiation therapy (EBRT), EBRT either alone or in combination with other LDT-3.6 percent of the overall cohort. EBRT in all subjects increased over time, with an average annual percent increase of 14 percent.
Nabavizadeh said that he expected the number to be much higher. "Using our own institutional experience, more than 4 percent of our patients get EBRT at some point, so 3.6 percent was a surprising figure to us," he said, "especially because radiation is the only non-invasive option and has not been shown to be inferior to the other treatments."
EBRT is a proven, established, safe, and effective treatment option for patients with unresectable liver cancer, yet its underutilization within this population highlights a real-world gap in treatment options available for patients with hepatocellular carcinoma, said Nabavizadeh. He and his colleagues found that, while the use of EBRT has increased over the past several years, it remains well below utilization for other therapies.
Transarterial chemoembolization or TACE, was the most utilized therapy, used for 39.6 percent of patients. Thermal ablation was used for 12.8 percent of patients, and radioembolization was used for 8.7 percent of patients. Nearly a quarter of patients (22.2%) received a combination of non-EBRT therapies.
Because there are no data supporting one treatment over another, institutional and regional practice patterns are often the key factor driving treatment, Nabavizadeh noted.
"Radiation oncologists are often left out of the management discussions for these patients," he said. "When presented with choices, many patients want the non-invasive approach. They understand this treatment could really impact their quality of life. Radiation needs to be part of treatment discussions much more frequently than it is now."
EBRT usage varied by geographic region, from a high of 8.7 percent of patients in the Great Lakes states (Michigan, Ohio, and Indiana) receiving this type of bridging therapy to a low of 1.7 percent of patients in the Southeast (Florida, Georgia, Mississippi, Alabama, Louisiana, and Arkansas).
EBRT utilization did not differ by clinical parameters, such as the number of tumors, tumor diameter, or bilirubin levels. While the study did not explore why patients were prescribed one treatment over another, Nabavizadeh suggested it could be a result of which type of doctor a patient consulted.
EBRT, and more explicitly stereotactic body radiation therapy, is a safe and effective bridging therapy to liver transplantation for patients with HCC. However, the national prevalence and clinicopathologic parameters of patients receiving EBRT as a bridging modality in the United States are unknown, he noted.
Liver-directed treatment options for patients awaiting transplant include: 1) thermal ablation procedures, which use advanced imaging technology to guide probes through the skin and into the liver to burn or freeze tumors at the site; catheter-based treatments including 2) trans-arterial chemoembolization (TACE) and 3) Y-90 radioembolization, where small particles are injected selectively into an artery directly supplying the tumor that cut off a tumor's blood supply and trap chemotherapy drugs or radioactive substances within the tumor; and (4) EBRT, which aims high doses of targeted radiation at tumor sites from outside the body using non-invasive techniques.
"In this first study, EBRT continues to be underutilized relative to other LDTs," Nabavizadeh said. "As an established safe and effective bridging therapy for HCC, low national utilization of EBRT (and in turn, SBRT) highlights a real-world gap in the treatment armamentarium for HCC and an opportunity to improve the care of patients with advanced liver disease needing liver transplantation."
Kurt Samson is a contributing writer.