SIR Today
Ideal thresholds for successful radiation segmentectomy CPN in HCC patients
Presentation: Monday, April 13, at 3 p.m. during the Radioembolization 2 session.
Z. Berman, C. De La Garza Ramos, S. Montazeri, K. Pianka, C. Malone, T. Sandow, J. Gimenez, S. Young, N. Fidelman, E. Kim, S. Padia, B. Toskich
A new U.S. multicenter study led by the COnsortium on Best Practice for Radiation Segmentectomy (COBRAS) evaluated which glass microsphere radiation segmentectomy treatment parameters most reliably produce complete pathologic necrosis (CPN) in hepatocellular carcinoma (HCC) patients awaiting liver transplantation.
“CPN has been established as a key outcome for patients with HCC treated with neoadjuvant therapies,” said Cynthia De La Garza Ramos, MD, who will present this abstract at SIR 2026. “IR is one of the major players in the management of HCC. Therefore, it is our responsibility to optimize radiation segmentectomy when clinically feasible.”
Researchers sought to validate the ablative capabilities of radiation segmentectomy for HCC prior to liver transplantation. Using Y‑90 glass microspheres (TheraSphere™), the investigators analyzed 364 treatment‑naive tumors from seven transplant centers between 2016 and 2024.
“We also sought to determine optimized treatment parameters beyond dose that authorized users can adapt to their practice to increase the possibility of achieving CPN,” Dr. De La Garza Ramos said.
All patients received radiation segmentectomy with glass microspheres prior to transplantation; those who did not proceed to transplant were excluded. The team compared dosimetric and technical variables between tumors that achieved CPN and those that did not.
According to the researchers, there was a direct correlation between the number of optimized parameters and CPN at liver transplantation, with a positive predictive value of 74% with one threshold met and 91% with all thresholds met (dose, microsphere activity, microsphere per milliliter and angiosome-to-tumor volume ratio).
The COBRAS data provides the first large, U.S.‑based consensus on dosimetric targets for radiation segmentectomy with glass microspheres. By adhering to the identified thresholds, researchers believe that IRs can reliably achieve CPN, which is strongly associated with lower recurrence rates and improved overall survival after transplantation.
“One of the major strengths of our study is the large and heterogeneous sample size, spanning patients from multiple major regions in the country,” Dr. De La Garza Ramos said. “We believe that it is powerful to have determined multiple treatment parameters as independent predictors of CPN as well as optimization thresholds, which can be applied by our colleagues.”
The findings also reinforce the need for device‑specific guidelines, given the distinct radiobiologic properties of glass versus resin microspheres. As this study only included patients treated with glass microspheres, extrapolation to resin microsphere usage or other available products should be done with caution, Dr. De La Garza Ramos said.
“Traditionally, resin and glass have had different microsphere activity and dosing values; though as commercially available pre-calibrated dates increase, these optimized parameters may apply.”
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