8:16 AM Abstract No. 61 - Splenomegaly-associated thrombocytopenia after hepatic Yttrium-90 radioembolization

Abstract

Purpose Thrombocytopenia is often observed after Yttrium-90 hepatic radioembolization (RE). Mechanisms may include direct radiation toxicity in the blood compartment, marrow suppression, or sequestration. We sought to identify the causative factors by retrospective analysis. Materials and Methods All patients with complete baseline and 3 month post-RE imaging and lab data were included in the analysis. Uni- and multivariate regression analysis were performed on clinical, procedural and imaging data, including white and red blood cell counts, administered Yttrium-90 activity and absorbed dose, territory treated, pre-existing cirrhosis, hepatopulmonary shunt fraction, and hepatic and splenic volumes. Results A total of 116 patients with complete datasets were identified (65 M, 51 F; median age 63; 46 primary, 70 secondary liver malignancy, 86 resin, 30 glass microspheres, median activity 1.85 GBq, median liver dose 45 Gy, 83 whole liver treatments). Median thrombocyte decrease was -20.2%, leading to new or increased grade of thrombocytopenia in 43 patients, by CTCAE-NCI version 4.02 criteria. One patient suffered grade 4 thrombocytopenia requiring transfusions. Independent risk factors for decrease in thrombocyte count included change in spleen volume (median change +17.5%; p Conclusion Post-RE treatment increase of spleen volume is correlated to decrease in peripheral thrombocyte count, suggesting a mechanism of increased portal hypertension and sequestration being responsible for thrombocytopenia.