Safety of Radioembolization in the Setting of Angiographically Apparent Arterioportal Shunting
The authors retrospectively evaluated all patients that underwent radioembolization for the treatment of HCC that also demonstrated angiographically apparent arterioportal shunting and investigated the association of adverse events with the different types of shunts. The authors divided the shunts into segmental, ipsilobar, contralobar and main lobar. Patients were excluded if the patients had undergone shunt mitigation techniques, had non-HCC liver malignancies or extrehepatic HCC, as well as insufficient follow up.
32 patients with 34 administrations were included with a median Na-MELD of 8.5. Patients underwent lobar and segmental treatments with >120 Gy and <120 Gy. Both glass and resin spheres were used. 28% of tumors were solitary, 22% multifocal and 50% infiltrative. 22% of patients were BCLC A, 12% B, 60% C and 6% D. Segmental shunts were seen in 35% of cases, ipsilobar 41%, contralobar 18% and main portal in 6%. Adverse events were graded using CTCAE version 4.0, and were considered significant if they were grade 3 or higher. The authors also analyzed CP class, ALBI grade, prior systemic chemotherapy, shunt direction and distribution, lobar vs. segmental dose administration and imaging of vascular invasion.
The authors found a statistical worsening of the ALBI score and a non-statistically significant trend to worsening of MELD and Na-MELD. A total of 15 AE were encountered, 7 of which were grade 3 or higher (22% clinically significant AEs). Radiation induced Liver Disease (ReILD) occurred in 4 patients, that showed lab abnormalities between 4-8 weeks, and death between 2-6 months. All ReILD cases were BCLC-C, underwent lobar administration and showed non-segmental shunts. This subgroup of patients had an AE rate of 38%, while the remainder of the cohort demonstrated AE rate of 12%. Response rates were higher for patients that presented with segmental shunts with 73% CR and 27% partial response. The overall survival for the cohort was 72% and 57% at 6 and 12 months respectively.
The authors found that all clinically significant AEs occurred in patients with non-segmental shunts. Furthermore, ReILD was seen in patients that presented with the triad of BCLC-C, non-segmental shunts and lobar Y90 administrations. A trend towards increased AEs was seen in patients that possessed this tried, with a clinically significant AE rate of 38%. No AE were seen in the resin Y90 patients, which the authors hypothesize could be due to the small sample of resin patients, the larger particle size or the lower dose when compared to glass spheres.
As far as response rates, both overall survival and initial response rates were similar to the current published outcomes.
The limitations of this study include the small sample, retrospective nature of the study and the heterogenous imaging follow up where MRI and CT were used.
The authors conclude that radioembolization in the setting of arterioportal shunting showed a variable safety profile. In one hand, segmental shunts appear to be well tolerated. On the other hand, caution should be taken in patients with advanced HCC stage, non-segmental shunts that undergo lobar administrations where clinically significant AEs were seen 38% of the time.
Figure- Early (1) and late (b) injection of the left hepatic artery demonstrates fugal shunting into the main portal vein (red arrows). (c) Demonstrates filling of the portal vein (yellow arrow) on the arterial phase scan.
The authors found that radioembolization appears to be safe and effective in HCC patients with angiographically apparent segmental shunts. While BCLC-C patients with non-segmental shunts that undergo lobar treatment are at higher risk for clinically significant AEs, including ReILD. More studies are necessary to validate the imaging outcomes and survival in this patient cohort, as well as the safety of resin spheres in patients with AP shuts, that in this study did not show any AEs.
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Thornton LM, Geller BS, Pepin EW, Shah JL, Kapp M, Toskich BB. Safety of Radioembolization in the Setting of Angiographically Apparent Arterioportal Shunting. J Vasc Interv Radiol. 2018 Nov;29(11):1511-1518. doi: 10.1016/j.jvir.2018.06.012. Epub 2018 Oct 5. PubMed PMID: 30293727
Carlos J. Guevara, MD
Department of Radiology, Interventional Radiology Division
University of Texas Health Sciences, Houston