Radioembolization with yittrium-90 (Y-90) is an established therapy for patients with hepatocellular carcinoma (HCC) and hepatic metastatic disease. Historically performed in a lobar fashion, radiation changes from Y-90 can lead to atrophy of the embolized, radiated hepatic parenchyma and compensatory hypertrophy of the contralateral lobe.
Dubbed “radiation lobectomy,” this technique has gained interest as an alternate approach to portal vein embolization (PVE) to facilitate surgical resection in patients with insufficient future liver remnants (FLR). Advantages of radiation lobectomy over portal vein embolization in achieving contralateral lobe hypertrophy include:
- Synchronous treatment of tumor in the embolized lobe
- Biologic test of time during FLR hypertrophy
- Less arterial blood flow redirection given the non-embolic nature of glass Y-90 particles
- No risk of portal vein blood flow compromise
These last two concepts are important in patients with HCC and underlying cirrhosis. Ultimately, patient selection is best done in multidisciplinary collaboration.
The technical approach to radiation lobectomy has evolved from simple lobar administration of Y-90 to modified approaches that promote boost tumor doses while ensuring hepatic parenchyma radiation to promote the atrophy-hypertrophy complex. The mechanism driving the atrophy-hypertrophy complex is not known; the optimal hepatic parenchymal radiation dose to achieve FLR hypertrophy has not been rigorously studied.
The successful funding of our research proposal highlights the importance for junior and mid-level investigators to have protected research time, training in clinical research and, most importantly, mentorship.
We have been awarded an R01 grant (1R01CA233878-01—“Yittrium-90 radiation lobectomy: Dose optimization and prediction of future liver remnant hypertrophy to enable resection of hepatocellular carcinoma”) to investigate the mechanism underlying radiation lobectomy. Our study seeks to determine the mechanism driving the atrophy-hypertrophy complex by combining multiple imaging modalities (Y-90-PET imaging, quantitative MR perfusion imaging, 4D flow MRI and MR-elastography) and circulating biomarkers with hepatic parenchymal changes from core liver biopsies and surgical explants. Our research team is multidisciplinary, combining expertise in interventional radiologists, MR/nuclear physics, MR imaging, hepatology and pathology. Led by interventional radiologists, this is important work to advance the field and enable definitive therapy to patients with HCC presenting with small FLR.
The successful funding of our research proposal highlights the importance for junior and mid-level investigators to have protected research time, training in clinical research and, most importantly, mentorship. In our opinion, research funding is critical to promote and support IR as a progressive, innovative specialty. IR program directors can foster future research success by ensuring that IR/DR residents are exposed to research throughout their training, emphasizing how this is critical to the advancement and ultimately long-term viability of IR as an American Board of Medical Specialty-recognized distinct specialty.
SIR Foundation plays an important role in supporting IR research and was essential in laying the foundation for our R01 grant. We had both been awarded Pilot Grant funding early in our careers; Dr. Collins’s funding led to preliminary data to support the MRI methods used in the radiation lobectomy R01 application. Importantly, through the SIR Foundation Pilot Grant, we established a track record of collaboration, which was essential when building the research team for this R01 grant.
Numerous IRs have successfully transitioned from society-level funding to government funding sources; however, our specialty needs to ensure that this effort continues and accelerates. IRs are on the leading edge in developing and performing novel, minimally invasive treatments. As we look into the future it is imperative that we also perform research demonstrating the efficacy of these therapies and continue to innovate. This will elevate the awareness of our specialty to patients and establish the outcomes data necessary to bring interventional therapies to patients earlier in the disease process.
Together, let’s encourage IR/DR residents and junior academic faculty to advance our specialty through science and innovation, defining the therapies of tomorrow through research.