Long-Term Toxicity after Transarterial Radioembolization with Yttrium-90 Using Resin Microspheres for Neuroendocrine Tumor Liver Metastases

Purpose: To evaluate long-term effects of yttrium-90 (⁹⁰Y) transarterial radioembolization (TARE) for unresectable hepatic metastases of neuroendocrine tumors (NETs). Materials and Methods: Retrospective analysis of 93 patients (47 women, 46 men; mean age 59 y) who underwent resin-based ⁹⁰Y TARE was performed. Variables associated with overall survival were analyzed using univariate and multivariate models. Changes in serologic values and imaging characteristics were assessed with long-term follow-up. Results: Unilobar TARE was performed in 48 patients, and staged bilobar TARE was performed in 45 patients. In multivariate analysis, ascites (P =.002) and extrahepatic metastases (P =.038) at baseline were associated with poor survival. Among 52 patients who had > 1 year of follow-up, significant increases in alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase were observed; however, only 4 patients experienced grade 3 serologic toxicities. Imaging signs of cirrhosis-like morphology and portal hypertension were observed in 15 of 52 patients, more frequently in patients treated with bilobar TARE compared with unilobar TARE. Patients treated with bilobar TARE exhibited significantly increased hepatobiliary enzymes and decreased platelet count. Sustained increases in liver enzymes were observed in patients with > 4 years of follow-up. No radioembolization-related liver failure or grade 4 toxicity was observed. Conclusions: ⁹⁰Y radioembolization using resin microspheres demonstrated a high safety profile for NET liver metastases, with low-grade, although sustained, long-term liver toxicity evident > 4 years after treatment. Bilobar treatment suggested a trend for treatment-related portal hypertension. Ongoing research will help define parameters for optimizing durable safety and efficacy of radioembolization in this setting.