PurposeWe aimed to evaluate the efficacy and outcomes of radioembolization with Yttrium-90 (Y-90) microspheres in patients with unresectable and chemorefractory colorectal cancer liver metastasis (CRCLM).MethodsThis single-center study included 43 patients (34 male, 9 female) who underwent radioembolization with Y-90 for unresectable, chemorefractory CRCLM between September 2008 and July 2014. Overall survival (OS), liver progression-free survival (LPFS), overall response rate (ORR), local disease control rate (LDCR), and relations of these parameters with patient disease characteristics were evaluated. OS and LPFS rates were compared according to microspheres. Survival rates were calculated with Kaplan-Meier method, and potential prognostic variables were evaluated on univariate analyses.ResultsPost-procedural median OS was 12.8months. LPFS was 5.6months. ORR was 33%, LDCR was 67% on 3rd month follow-up. Low tumor burden (<25%) was associated with higher median OS after radioembolization (<25 vs >25-50% p<0.0001 and <25 vs >50% p=0.005). Patients with left colon tumors exhibited significantly longer median OS after metastasis than right colon tumors (p=0.046). Extrahepatic disease and synchronicity showed poorer survival parameters; however, the difference was not significant (p=0.1 and p=0.3, respectively). In subgroup analyses, the distribution of patient number and characteristics showed heterogeneity as number of patients with low tumor burden was higher in resin Y-90 group. Resin Y-90 group exhibited significantly higher median OS and LPFS compared to glass Y-90 group (16.5 vs. 7months, p=0.001; 6.73 vs. 3.38months, p=0.023, respectively).ConclusionRadioembolization is a safe local-regional treatment option in chemorefractory, inoperable CRCLM. Radioembolization at earlier stages may lead to more favorable results especially with lower tumor burden patients.