Abstract No. 72 Yttrium-90 Radioembolization Treatment of Patients with Liver-Dominant Metastatic Renal Cell Carcinoma

The median overall survival (OS) of patients with liver-dominant metastatic renal cell carcinoma (RCC) treated with chemotherapy was reported to be 7.6 months. The purpose of this study was to evaluate the safety and efficacy of Yttrium-90 (Y90) radioembolization of patients with liver-dominant metastatic RCC. This institutional review board-approved, single-center, retrospective study included 36 patients with liver-dominant RCC who underwent radioembolization with Y90-labeled glass microspheres between January 2009 and December 2019. Medical records and imaging data were reviewed to evaluate toxicities, tumor response, overall survival (OS) and liver-progression-free survival (LPFS). Median follow-up time was 18.2 months (range, 1.5-115.2). 20 patients received systemic therapy before and 28 patients after radioembolization. Median OS was 19.3 months (95% CI: 10.1-43.5) from radioembolization and 36.5 months (95% CI: 26.4-49.8) from liver metastasis diagnosis. LPFS was 9.5 months (95% CI: 8.0-17.7). At 3-month follow-up 22 patients reported mild, grade 1-2 clinical toxicities (17 fatigues, 5 nausea, 4 abdominal pain, 2 decreased appetite). Two patients developed biliary stricture (grade 3) that required drainage. Grade 1 and 2 biochemical toxicities was found in 27 patients. Objective tumor response was achieved in 32 patients (21 CR, 11 PR) whereas 1 patient had stable disease and 2 patients had progressive disease using the modified Response Evaluation Criteria for Solid Tumors (mRECIST). One patient had non-contrast imaging showing stable disease per RECIST. On multivariate analysis objective imaging response (P = 0.001, HR 48.28), shorter time from liver metastasis diagnosis to Y90 treatment (P = 0.04, HR 1.00), higher albumin level (P = 0.003, HR 0.15) and lower MELD score (P = 0.01 HR 1.17) were associated with longer median OS. Radioembolization is safe and effective in patients with liver-dominant RCC and provides good hepatic tumor control and improved OS compared to chemotherapy alone. The current study supports the role of radioembolization in the treatment protocol of liver-dominant metastatic RCC.