Outcomes Analysis of 90Y Radioembolization for Tumors Other Than Metastatic Colorectal Cancer from the RESiN (Radiation-Emitting SIR-spheres in Non-resectable liver tumors) Registry.

PURPOSE: To characterize the response and survival outcomes of yttrium-90 transarterial radioembolization (90Y-TARE) for unresectable, liver-dominant metastases from primary neoplasms other than colorectal carcinoma. MATERIALS AND METHODS: This study included 1474 patients enrolled in the RESiN registry who received resin 90Y-TARE as part of their oncologic management for unresectable primary or secondary liver tumors (NCT02685631). 33% (481/1474) were treated for liver metastases of non-colorectal origin (m-nonCRC), compared to 34% (497/1474) treated for colorectal liver metastases (mCRC) and 34% (496/1474) treated for hepatocellular carcinoma (HCC). Treatment response and cancer survival probabilities were computed and compared for each primary cancer type. The Kaplan-Meier method and log-rank test were used to compare survival outcomes. RESULTS: Radiological responses were observed in 12 unique cancer types, mostly heavily pre-treated malignancies refractory to multiple lines of systemic therapies. The overall use of resin 90Y-TARE in m-nonCRC resulted in better treatment outcomes in terms of duration of response, progression free survival, time to progression and overall survival (P = 0.04, P = 0.02, P = 0.01, P = 0.04). Analyses of cancer cell types revealed that metastatic neuroendocrine tumor, sarcoma, and ovarian, renal, prostate, and breast cancers were associated with superior treatment outcomes, whereas worse treatment outcomes were observed in metastatic lung, gastric, pancreatic and esophageal cancers. CONCLUSION: Real-world data demonstrate the use of resin 90Y-TARE in m-nonCRC refractory to standard chemotherapy. For some cell types, this expanded use achieved superior treatment outcomes relative to the reference standard of mCRC, suggesting the need for inquiry into broadened indications for 90Y-TARE.

Consensus Statement on Safety of Combining Transarterial Radioembolization with Yttrium-90 Microspheres with Systemic Anticancer Agents for the Treatment of Liver Malignancy.

PURPOSE: To provide guidance, via multidisciplinary consensus statements, on the safety interactions between systemic anticancer agents (such as radiosensitizing chemotherapy, immunotherapy, targeted therapy, and peptide receptor radionuclide therapy) and transarterial radioembolization (TARE) with yttrium-90 (90Y)-labeled microspheres in the treatment of primary and metastatic liver malignancies. MATERIALS AND METHODS: A literature search identified 59 references that informed 26 statements on the safety of 90Y TARE combined with systemic therapies. Modified Delphi method was used to develop consensus on statements through online anonymous surveys of the 12 panel members representing the fields of interventional radiology, medical oncology, surgical oncology, hepatology, and pharmacy, focusing on hepatocellular carcinoma (HCC), metastatic colorectal cancer (mCRC), neuroendocrine tumors, metastatic breast cancer, and intrahepatic cholangiocarcinoma. RESULTS: High-level evidence was limited. Level 1 data in patients with mCRC suggest that some radiosensitizing chemotherapies (eg, oxaliplatin) require temporary dose reduction when used concomitantly with 90Y TARE, and some targeted therapies (eg, vascular endothelial growth factor inhibitors and antiangiogenic tyrosine kinase inhibitors) should be avoided for at least 4 weeks before 90Y TARE. In patients with HCC, the feasibility of 90Y TARE and immunotherapy has been demonstrated with Level 4 evidence. Data are more limited for other primary and secondary liver malignancies, and consensus statements were driven by expert opinion (Level 5). CONCLUSIONS: Given the absence of evidence-based guidelines on the safety of 90Y TARE in combination with systemic anticancer therapy, these consensus statements provide expert guidance on the potential risks when considering specific combinations.

Simulation of Image-Guided Microwave Ablation Therapy Using a Digital Twin Computational Model.

Emerging computational tools such as healthcare digital twin modeling are enabling the creation of patient-specific surgical planning, including microwave ablation to treat primary and secondary liver cancers. Healthcare digital twins (DTs) are anatomically one-to-one biophysical models constructed from structural, functional, and biomarker-based imaging data to simulate patient-specific therapies and guide clinical decision-making. In microwave ablation (MWA), tissue-specific factors including tissue perfusion, hepatic steatosis, and fibrosis affect therapeutic extent, but current thermal dosing guidelines do not account for these parameters. This study establishes an MR imaging framework to construct three-dimensional biophysical digital twins to predict ablation delivery in livers with 5 levels of fat content in the presence of a tumor. Four microwave antenna placement strategies were considered, and simulated microwave ablations were then performed using 915 MHz and 2450 MHz antennae in Tumor Naïve DTs (control), and Tumor Informed DTs at five grades of steatosis. Across the range of fatty liver steatosis grades, fat content was found to significantly increase ablation volumes by approximately 29-l42% in the Tumor Naïve and 55-60% in the Tumor Informed DTs in 915 MHz and 2450 MHz antenna simulations. The presence of tumor did not significantly affect ablation volumes within the same steatosis grade in 915 MHz simulations, but did significantly increase ablation volumes within mild-, moderate-, and high-fat steatosis grades in 2450 MHz simulations. An analysis of signed distance to agreement for placement strategies suggests that accounting for patient-specific tumor tissue properties significantly impacts ablation forecasting for the preoperative evaluation of ablation zone coverage.

Predictive Dosimetry and Outcomes of Hepatocellular Carcinoma Treated by Yttrium-90 Resin Microsphere Radioembolization: A Retrospective Analysis Using Technetium-99m Macroaggregated Albumin SPECT/CT and Planning Software.

PURPOSE: To characterize estimated mean absorbed tumor dose (ADT), objective response (OR), and estimated target dose of hepatocellular carcinoma (HCC) after resin microsphere yttrium-90 (90Y) radioembolization using partition dosimetry. MATERIALS AND METHODS: In this retrospective, single-center study, multicompartment dosimetry of index tumors receiving 90Y radioembolization between October 2015 and June 2022 was performed using a commercial software package and pretreatment technetium-99m macroaggregated albumin single photon emission computed tomography (SPECT)/computed tomography (CT). In total, 101 patients with HCC underwent 102 treatments of 127 index tumors. Patients underwent imaging every 2-3 months after treatment to determine best response per modified Response Evaluation Criteria in Solid Tumors (mRECIST). Best response was defined as the greatest response category per mRECIST and categorized as OR or nonresponse (NR). A Cox proportional hazards model evaluated the probability of tumor OR and progression-free survival using ADT. RESULTS: The median follow-up period was 148 days (interquartile range [IQR], 92-273 days). The median ADT of OR was 141.9 Gy (IQR, 89.4-215.8 Gy) compared with the median ADT of NR treatments of 70.8 Gy (IQR, 42.0-135.3 Gy; P < .001). Only ADT was predictive of response (hazard ratio = 2.79 [95% confidence interval {CI}: 1.44-5.40]; P = .003). At 6 months, an ADT of 157 Gy predicted 90.0% (95% CI: 41.3%-98.3%) probability of OR. At 1 year, an ADT of 157 Gy predicted 91.6% (95% CI: 78.3%-100%) probability of progression-free survival. Partition modeling and delivered activity were predictive of progression (P = .021 and P = .003, respectively). CONCLUSIONS: For HCC treated with resin microspheres, tumors receiving higher ADT exhibited higher rates of OR. An ADT of 157 Gy predicted 90.0% OR at 6 months.

Partition Dosimetry and Outcomes of Metastatic Neuroendocrine Tumors after Yttrium-90 Resin Microsphere Radioembolization.

PURPOSE: To characterize estimated mean tumor-absorbed dose (ADT) and objective response of metastatic neuroendocrine tumor (NET) after resin microsphere yttrium-90 (90Y) hepatic radioembolization using partition dosimetry. MATERIALS AND METHODS: In this retrospective, single-center study, multicompartment dosimetry of index tumors receiving 90Y radioembolization between 2013 and 2022 involved the use of Sureplan (MIM Software, Cleveland, Ohio) and technetium-99m macroaggregated albumin single photon emission computed tomography (SPECT) combined with computed tomography. Thirty-six patients with NET underwent treatment of 56 index tumors. Patients underwent imaging every 3-6 months after treatment to determine best response per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 and modified RECIST (mRECIST) criteria. Responses were categorized as objective response (OR) or nonresponse (NR). Wilcoxon rank sum test evaluated differences in continuous variables, and Pearson χ2 test evaluated differences in categorical variables. RESULTS: Median follow-up was 582 days (IQR, 187-1,227 days). Per RECIST 1.1, 27 patients (75%) experienced OR and 9 patients experienced (25%) NR. Of the 36 patients, 33 (92%) showed hypervascular, mRECIST-evaluable tumors. Among them, 28 patients (85%) showed mRECIST OR and 5 patients (15%) showed NR. The mRECIST OR group received a higher ADT than the NR group (median, 107 Gy; IQR, 95.1-154 Gy vs median, 70.4 Gy; IQR, 62.9-87.6 Gy; P = .048). All tumors receiving at least 120 Gy showed mRECIST OR. CONCLUSIONS: In hypervascular metastatic NET treated by 90Y resin microsphere radioembolization, higher tumor dose was associated with better tumor response per mRECIST. Doses of ≥120 Gy led to OR.

Effect of Previous Transarterial Chemoembolization on Survival and Toxicity after Yttrium-90 Transarterial Radioembolization of Hepatocellular Carcinoma in the Radiation-Emitting SIR-Spheres in Nonresectable Liver Tumor Registry.

PURPOSE: To determine overall survival (OS), best response, and toxicities in patients with hepatocellular carcinoma (HCC) previously treated with chemoembolization (TACE+) or yttrium-90 resin transarterial radioembolization (TARE) compared with those of TACE-naïve (T-N) participants. MATERIALS AND METHODS: In this prospective, observational study, 262 adult participants with HCC were divided into TACE+ (n = 93, 35%) or T-N (n = 169, 65%) groups, included from 36 centers in the United States. Overall survival (OS) was assessed using Kaplan-Meier analysis from the date of TARE. Best response at 6 months was evaluated using modified Response Evaluation Criteria in Solid Tumors. Six-month toxicities were reported using Common Terminology Criteria for Adverse Events, version 5. RESULTS: Median OS for patients in the TACE+ and T-N groups was 22.3 months (95% CI: 17.2 to not reachable) and 21.5 months (95% confidence interval [CI]: 14.9-29.9), respectively (P = .6). Imaging at 6 months ± 2 weeks was available in 156 of 262 (60%) participants. Partial or complete response was seen in 27 of 55 patients (49%) in the TACE+ group and 65 of 101 patients (64%) in the T-N group (P = .2). Six-month toxicities were available in 69 of 93 patients (74%) in the TACE+ group and 135 of 167 patients (81%) in the T-N group. Attributable Grade 3 or greater liver function toxicities were similar between the study groups (all P > .05). CONCLUSIONS: OS and imaging response at 6 months in the TACE+ group was similar to that in the T-N group with similar toxicities. Radioembolization is an acceptable treatment option for patients with HCC previously treated with TACE.

Predictive Partition Dosimetry and Outcomes after Yttrium-90 Resin Microsphere Radioembolization of Colorectal Cancer Metastatic to the Liver: A Retrospective Analysis.

PURPOSE: To characterize estimated absorbed tumor dose (ADT), objective response (OR), and estimated target dose of liver metastatic colorectal cancer (mCRC) after resin microsphere yttrium-90 (90Y) radioembolization using partition dosimetry. MATERIALS AND METHODS: In this retrospective, single-center study, multicompartment dosimetry of index tumors undergoing 90Y radioembolization from October 2013 to July 2022 was performed using MIM SurePlan and pretreatment technetium-99m macroaggregated albumin infusion data. Thirty-eight patients with mCRC underwent treatments for 59 index tumors. Patients were imaged every 2-3 months after treatment and then every 3-6 months after disease control to determine the best response per Response Evaluation Criteria in Solid Tumors 1.1. Responses were categorized as OR or nonresponse (NR). A Cox proportional hazards model evaluated the probability of tumor OR and local progression-free survival (LPFS) based on ADT. RESULTS: Patients had a median follow-up of 116 days (interquartile range [IQR], 69-231 days). The ADT was higher for OR patients than for NR patients (median, 130.8 [IQR, 85.6-239.0] vs 40.6 [IQR, 26.0-66.3] Gy; P < .001). A greater percentage of OR than NR patients were treated with activities calculated by partition modeling (54% vs 12%; P = .005). Only ADT predicted response (P = .032). At 6 months, an ADT of 120 Gy predicted a 55% (95% CI, 0.0%-89%) probability of OR. Only ADT (P = .010) and female sex (P = .014) predicted LPFS. At 1 year, an ADT of 120 Gy predicted a 70% (95% CI, 35%-100%) probability of LPFS. CONCLUSIONS: Tumor dose was the strongest predictor of OR for mCRC. Administration of an estimated 120 Gy to mCRC predicted 55% OR with 90Y resin microspheres at 6 months.

Overall survival and toxicity of hepatocellular carcinoma Barcelona Clinic Liver Cancer B patients receiving Y90 radioembolization: analysis of the radiation-emitting SIR-spheres in non-resectable liver tumor (RESiN) registry.

Background: To evaluate overall survival (OS), progression-free survival (PFS) and toxicity after resin Yttrium-90 (Y-90) radioembolization in Barcelona Clinic Liver Cancer B (BCLC B) hepatocellular carcinoma (HCC) patients using the Bolondi subgroup classification. Methods: A total of 144 BCLC B patients were treated between 2015-2020. Patients were broken into 4 subgroups by tumor burden/liver function tests with 54, 59, 8 and 23 in subgroups 1, 2, 3 and 4. OS and PFS were calculated with Kaplan-Meier analysis with 95% confidence intervals. Toxicities were assessed using Common Terminology Criteria for Adverse Events (CTCAE) v5. Results: Prior resection and chemoembolization were performed in 19 (13%) and 34 (24%) of patients. There were no deaths within 30 days. Median OS and PFS for the cohort were 21.5 and 12.4 months. Median OS was not reached for subgroup 1 at a mean 28.8 months, and was 24.9, 11.0 and 14.6 months for subgroups 2-4 (χ2=19.8, P=0.0002). PFS by BCLC B subgroup was 13.8, 12.4, 4.5, and 6.6 months (χ2=16.8, P=0.0008). The most common Grade 3 or 4 toxicities were elevated bilirubin (n=16, 13.3%) and decreased albumin (n=15, 12.5%). Grade 3 or greater bilirubin (32% vs. 10%, P=0.03) and albumin (26% vs. 10%, P=0.03) toxicity were more common in the subgroup 4 patients. Conclusions: The Bolondi subgroup classification stratifies OS, PFS and development of toxicity in patients treated with resin Y-90 microspheres. OS in subgroup 1 approaches 2.5 years and Grade 3 or greater hepatic toxicity profile in subgroups 1-3 is low.

Recurrent Portal Vein Thrombosis In Liver Transplantation With Renoportal Anastomosis Caused by Spontaneous Reno-Caval Shunts: A Case Report.

BACKGROUND: Orthotopic liver transplantation (OLT) in patients with cirrhosis complicated by portal hypertension, portosystemic shunts, and chronic portal vein thrombosis (PVT) has long been challenging. Spontaneous spleno-renal shunts (SRS) allow new surgical techniques to restore portal vein patency and hepatopetal flow. Renoportal anastomosis (RPA) has emerged as an accepted method for transplanting these patients, with good long-term patient and graft survival. Orthotopic liver transplantation with RPA is known to be complicated by recurrent PVT, with few details discussed in the literature. CASE REPORT: We present a case of a 56-year-old woman with decompensated cirrhosis who underwent deceased donor whole graft OLT using RPA with iliac vein conduit. The postoperative course was complicated by occlusive thrombosis in the portal vein and iliac vein conduit. Venography revealed enlarged left gonadal and lumbar vein varices acting as reno-caval shunts with hepatofugal flow. Embolization of the varices re-established durable venous patency that was confirmed on post-transplant day 68 with no other hemodynamic complications. DISCUSSION: This showcases an interesting mechanism by which recurrent PVT may occur in patients undergoing OLT with RPA. Because durable portal vein patency can be achieved with Interventional Radiology embolization of reno-caval varices, assessing these communications is an important preoperative consideration for planned OLT with RPA.

Survival and Toxicities after Yttrium-90 Transarterial Radioembolization of Cholangiocarcinoma in the RESiN Registry.

PURPOSE: To report outcomes in patients with intrahepatic cholangiocarcinoma treated with yttrium-90 resin microspheres (transarterial radioembolization [TARE]) from a multicenter, prospective observational registry. MATERIALS AND METHODS: Ninety-five patients (median age, 67 years [interquartile range {IQR}, 59-74]; 50 men) were treated in 27 centers between July 2015 and August 2020. Baseline demographic characteristics included imaging findings, performance status, and previous systemic or locoregional treatments. Dosimetry method was tracked. Overall survival (OS) and progression-free survival were calculated using the Kaplan-Meier method. The best imaging response was calculated using the Response Evaluation Criteria in Solid Tumors v1.1. Grade ≥3 toxicities were assessed using Common Terminology Criteria for Adverse Events v5. Cox regression analysis was performed. RESULTS: Fifty-two of 86 (60%) patients had multifocal tumors, and 24/89 (27%) had extrahepatic tumors. The median index tumor diameter was 7.0 cm (IQR, 4.9-10 cm). The activity calculation method was reported in 59/95 (62%) patients, with body surface area being the most frequently used method (45/59, 76%). Median OS for the cohort was 14 months (95% confidence interval, 12-22). OS at 3, 6, 12, and 24 months was 94%, 80%, 63%, and 34%, respectively. Median OS was longer in patients without cirrhosis (19.1 vs 12.2 months, P = .05). Cirrhosis, previous chemotherapy (OS, 19.1 vs 10.6 months for treatment-naïve; P = .07), and imaging response at 6 months (OS, 16.4 vs 9.5 months for no response; P = .06) underwent regression analysis. Imaging response predicted OS at regression (hazard ratio, 0.39; P = .008). Grade 3-4 bilirubin toxicities were noted in 5 of 72 (7%) patients. Grade 3 albumin toxicity was noted in 1 of 72 (1.4%) patients. CONCLUSIONS: Objective response at 6 months predicted longer OS after TARE for intrahepatic cholangiocarcinoma. The incidence of liver function toxicity was <10%.

Six-Year Evaluation of Same-Day Discharge following Conventional Transarterial Chemoembolization of Hepatocellular Carcinoma.

PURPOSE: To evaluate whether same-day discharge increased the incidence of 30-day readmission (30dR) after conventional transarterial chemoembolization (TACE) for hepatocellular carcinoma (HCC) at a single institution. MATERIALS AND METHODS: In this retrospective study, 253 patients with HCC underwent 521 transarterial chemoembolization procedures between 2013 and 2020. TACE was performed with 50-mg doxorubicin/10-mg mitomycin C/5-10-mL ethiodized oil/particles. Patients not requiring intravenous pain medications were discharged after a 3-hour observation, and 30dR was tracked. The primary objective was to determine the incidence of 30dR in same-day discharge patients versus patients admitted for observation using the chi-square test. Secondary objectives assessed factors associated with overnight admission and factors predictive of 30dR using generalized estimated equation calculations and logistic regression. RESULTS: In the cohort, 24 readmissions occurred within 30 days (4.6%). Same-day discharge was completed after 331 TACE procedures with sixteen 30dRs (4.8%). Patients admitted overnight were readmitted 8 times after 190 TACE procedures (4.2%). This difference was not statistically significant (P = .4). Factors predicting overnight admission included female sex (58/190 [30.5%] vs 58/331 [17.5%], P < .001) and tumor size of ≥3.8 cm (104/190 [55%] vs 85/190 [45%]). Factors predicting 30dR included female sex (10/116 [8.6%] vs 14/405 [0.2%]) and younger age (median [interquartile range], 63 years [55-65 years] vs 65 years [59-71 years]). At regression, factors predictive of 30dR were Child-Pugh Class B/C (odds ratio [OR], 2.1; P = .04) and female sex (OR, 2.9; P = .004). CONCLUSIONS: Same-day discharge after conventional TACE is a safe and effective strategy with 30dR rate of <5%, similar to overnight observation.

Overall survival and toxicity of Y90 radioembolization for hepatocellular carcinoma patients in Barcelona Clinic Liver Cancer stage C (BCLC-C).

INTRODUCTION: National Comprehensive Cancer Network HCC guidelines recommend Y90 to treat BCLC-C patients only in select cases given the development of systemic regimens. We sought to identify ideal candidates for Y90 by assessing survival and toxicities in this patient group. MATERIALS AND METHODS: The Radiation-Emitting Selective Internal radiation spheres in Non-resectable tumor registry is a prospective observational study (NCT: 02,685,631). Patients with advanced HCC were stratified into 3 groups based on tumor location, Eastern Cooperative Oncology Group (ECOG) performance status, and liver function. Group 1: liver isolated HCC, ECOG 0 and Child Pugh (CP) A (n = 12, 16%), Group 2: liver isolated HCC, ECOG ≥ 1 or CP B/C (n = 37, 49%), and Group 3: extrahepatic HCC with any ECOG or CP score (n = 26, 35%). Patients in any group could have macrovascular invasion. Overall survival (OS) and progression-free survival (PFS) with 95% confidence intervals (95% CI) were calculated. Grade 3 + toxicities were tracked using Common Terminology Criteria for Adverse Events v5. Cox proportional hazard model was performed to determine factors affecting OS. RESULTS: Seventy-five BCLC-C patients treated between 2015 and 2019 were reviewed. The groups were similar in age, sex, race, and ethnicity (all p > 0.05). Bilobar disease was least common in Group 1 (p < 0.001). Median OS of the entire cohort was 13.6 (95% CI 7.5-16.1) months. Median OS of Groups 1-3 were 21.8, 13.1 and 11.5 months respectively (p = 0.6). Median PFS for the cohort was 6.3 (4.8-14.7) months. Median PFS for group 1 was not reached. Mean PFS for Group 1 was 17.3 ± 4.8 months. Median PFS for Groups 2 and 3 was 6.8 and 5.9 months (X2 = 1.5, p = 0.5). Twenty-four Grade 3 or greater toxicities developed, most commonly hyperbilirubinemia (8/75, 11%) and thrombocytopenia (2/75, 3%). The incidence of toxicities between groups was similar (all p > 0.05). Cox Proportional Hazard analysis predicted shorter OS with CP class B/C (X2 = 6.7, p = 0.01), while macrovascular invasion (X2 = 0.5, p = 0.5) and ECOG score of ≥ 1 (X2 = 2.1, p = 0.3) was not associated with OS. CONCLUSIONS: OS of CPA patients with advanced HCC and performance status of 0 was 21.8 months following Y90. CP A cirrhosis is the best predictor of prolonged OS in advanced (BCLC-C) HCC.

Role of Radioembolization in Metastatic Neuroendocrine Tumors.

The liver is the most common site of metastasis for neuroendocrine tumors originating from the gastrointestinal tract. Neuroendocrine liver metastases (NELMs) portend a worsening clinical course, making local management important. Local treatment options include surgery, thermal ablation, and trans-catheter intra-arterial therapies, such as radioembolization. Radioembolization is generally preferred over other embolotherapies in patients with colonized biliary systems. Current best practice involves personalized treatment planning, optimizing tumor radiation absorbed dose and minimizing radiation to the normal hepatic parenchyma. As part of a multidisciplinary approach, radioembolization is a versatile embolotherapy offering neoadjuvant, palliative, and ablative treatment options for patients with NELMs.

Survival and Toxicities after 90Y Transarterial Radioembolization of Metastatic Colorectal Cancer in the RESIN Registry.

Background Patients with unresectable, chemorefractory hepatic metastases from colorectal cancer have considerable mortality. The role of transarterial radioembolization (TARE) with yttrium 90 (90Y) microspheres is not defined because most reports are from a single center with limited patient numbers. Purpose To report outcomes in participants with colorectal cancer metastases treated with resin 90Y microspheres from a prospective multicenter observational registry. Materials and Methods This study treated enrolled adult participants with TARE using resin microspheres for liver-dominant metastatic colorectal cancer at 42 centers, with enrollment from July 2015 through August 2020. TARE was used as the first-, second-, or third-line therapy or beyond. Overall survival (OS), progression-free survival (PFS), and toxicity outcomes were assessed by line of therapy by using Kaplan-Meier analysis for OS and PFS and Common Terminology Criteria for Adverse Events, version 5, for toxicities. Results A total of 498 participants (median age, 60 years [IQR, 52-69 years]; 298 men [60%]) were treated. TARE was used in first-line therapy in 74 of 442 participants (17%), second-line therapy in 180 participants (41%), and third-line therapy or beyond in 188 participants (43%). The median OS of the entire cohort was 15.0 months (95% CI: 13.3, 16.9). The median OS by line of therapy was 13.9 months for first-line therapy, 17.4 months for second-line therapy, and 12.5 months for third-line therapy (χ2 = 9.7; P = .002). Whole-group PFS was 7.4 months (95% CI: 6.4, 9.5). The median PFS by line of therapy was 7.9 months for first-line therapy, 10.0 months for second-line therapy, and 5.9 months for third-line therapy (χ2 = 8.3; P = .004). TARE-attributable grade 3 or 4 hepatic toxicities were 8.4% for bilirubin (29 of 347 participants) and 3.7% for albumin (13 of 347). Grade 3 and higher toxicities were greater with third-line therapy for bilirubin (P = .01) and albumin (P = .008). Conclusion Median overall survival (OS) after transarterial radioembolization (TARE) with yttrium 90 microspheres for liver-dominant metastatic colorectal cancer was 15.0 months. The longest OS was achieved when TARE was part of second-line therapy. Grade 3 or greater hepatic function toxicity rates were less than 10%. Clinical trial registration no. NCT02685631 Published under a CC BY 4.0 license. Online supplemental material is available for this article. See also the editorial by Liddell in this issue.