The Role of Tumor Vascularity in Predicting Survival after Yttrium-90 Radioembolization for Liver Metastases

Purpose: It is unclear what role pretreatment tumor vascularity plays in determining outcomes after yttrium-90 radioembolization. A hypothesis was tested that radiographic vascularity of a tumor does not affect patient survival. Materials and Methods: In this two-institution retrospective study, 137 patients with metastatic liver disease underwent ⁹⁰Y radioembolization. Primary sites were categorized as colon, neuroendocrine, and other. All patients underwent triphasic contrast-enhanced computed tomography (CT) or magnetic resonance imaging, as well as detailed hepatic angiography. Two board-certified interventional radiologists interpreted all images and evaluated them for the presence of enhancement. Median survival times, as well as 1- and 2-year survival rates, were compared between patients with hypervascular and hypovascular tumors on (i) cross-sectional imaging and (ii) angiography with use of the log-rank statistic (α = 0.05). Results: On angiography, 108 patients had hypervascular tumors and 29 had hypovascular tumors. Median survival times for the two subgroups were 300 days and 261 days, respectively (P = .95). On CT, 24 patients had hypervascular tumors and 113 had hypovascular tumors. Median survival times for these subgroups were 306 days and 284 days, respectively (P = .67). Eighty-four patients' tumors that were hypovascular on CT were hypervascular on angiography. There were no statistical differences in survival between patients with hypervascular and hypovascular tumors, regardless if vascularity was defined based on CT or angiography. Conclusions: Radiographic vascular appearance of liver tumors, regardless of imaging modality, does not affect survival after radioembolization. Therefore, hypovascular tumors should not be considered contraindicated for radioembolization.