Abstract
PurposeTreatment efficacy of intra-arterial radioembolization for liver tumors depends on the selective targeting of tumorous tissue. Recent investigations have demonstrated that tumors may receive inadequate doses of radioactivity after radioembolization, due to unfavorable tumor to non-tumor (T/N) uptake ratios of radioactive microspheres. Hepatic arterial infusion of the vasoconstrictor angiotensin II (AT-II) is reported to increase the T/N blood flow ratio. The purpose of this systematic review was to provide a comprehensive overview of the effect of hepatic arterial AT-II on T/N blood flow ratio in patients with hepatic malignancies, and determine its clinical value for radioembolization.MethodsThis review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A structured search was performed in the PubMed, EMBASE and Cochrane databases. Only studies that presented data on T/N ratios before and after infusion of AT-II into the hepatic artery, in human patients with hepatic malignancies, were selected. Median T/N ratios before, during and after AT-II infusion, and the median T/N ratio improvement factor were extracted from the selected articles. All data on systemic blood pressure measurements and clinical symptoms were also extracted.ResultsThe search identified 524 titles of which 5 studies, including a total of 71 patients were considered relevant. Median T/N ratios before infusion of AT-II ranged from 0.4 to 3.4. All studies observed a substantial improvement of the T/N ratio after AT-II infusion, with median improvement factors ranging from 1.8 to 3.1. A transitory increase of systemic blood pressure was observed during AT-II infusion.ConclusionsInfusion of AT-II into the hepatic artery leads to an increase of the tumor to non-tumor blood flow ratio, as measured by T/N uptake ratios. Clinical trials are warranted to assess safety aspects, optimal administration strategy and impact on treatment efficacy during radioembolization.
Highlights
Intra-arterial radioembolization (RE) with yttrium-90 (90Y-) microspheres has proven to be an effective treatment option for patients with unresectable primary or metastatic liver tumors, refractory to chemotherapy.[1,2,3,4,5] During this minimallyinvasive therapy, a percutaneous approach is used to place a catheter in the hepatic artery and administer high-energy bradiation emitting 90Y-microspheres that will irradiate liver tumors from within
All studies observed a substantial improvement of the to nontumor (T/N) ratio after angiotensin II (AT-II) infusion, with median improvement factors ranging from 1.8 to 3.1
Infusion of AT-II into the hepatic artery leads to an increase of the tumor to non-tumor blood flow ratio, as measured by T/N uptake ratios
Summary
Intra-arterial radioembolization (RE) with yttrium-90 (90Y-) microspheres has proven to be an effective treatment option for patients with unresectable primary or metastatic liver tumors, refractory to chemotherapy.[1,2,3,4,5] During this minimallyinvasive therapy, a percutaneous approach is used to place a catheter in the hepatic artery and administer high-energy bradiation emitting 90Y-microspheres that will irradiate liver tumors from within. Several studies reported that favorable T/N uptake ratios of 99mTc- MAA are associated with improved post-treatment tumor response[7,8,9], whereas other studies contradict these findings and emphasize that assuming an equal intrahepatic distribution of 99mTc-MAA and 90Y-microspheres may not be justified.[10,11,12,13] Still, a consistent finding of these studies is a strong interindividual heterogeneity in T/N uptake ratio’s, with a reported range of 0.6–
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