Purpose: Portal vein tumor thrombosis (PVTT) from cancer involving the liver carries a dismal prognosis, with median overall survival (OS) ranging from 2 to 5 months. While treatment with yttrium-90 (90Y) radioembolization alone may improve outcomes, overall prognosis remains poor. We hypothesize that the combination of 90Y radioembolization to the parenchymal component of the tumor and stereotactic body radiation therapy (SBRT) to the vascular component is a safe and effective means of improving outcomes. Materials and Methods: A single center retrospective review identified 12 patients with cancers involving the liver who received both 90Y radioembolization and SBRT to the PVTT between May 2015 to August 2020. Primary endpoint was the 90-day toxicity rate by the Common Terminology Criteria for Adverse Events version 5.0. Secondary endpoints were the best response rate based on the Response Evaluation Criteria in Solid Tumors v1.1, local control rate, portal vein (PV) patency rate, and median OS. Results: Patients received a median 90Y dose of 104.3 Gy (range, 83.3 to 131.7 Gy) and a median 5-fraction SBRT dose of 32.5 Gy (range, 27.5 to 50 Gy). There were no late toxicities reported, and only 7 acute grade 1 toxicities reported: elevation of liver function tests (17%), nausea (17%), fatigue (17%), and esophagitis (8%). Local control was 83%. 58% of patients had a patent PV after treatment. With a median follow-up time of 28 months, 1-year OS was 55% with a median OS of 14 months. Conclusion Combination 90Y radioembolization and SBRT appears to be safe and effective in the treatment of PVTT. Larger prospective studies are warranted to better evaluate this combination treatment approach.

Purpose: Portal vein tumor thrombosis (PVTT) from cancer involving the liver carries a dismal prognosis, with median overall survival (OS) ranging from 2 to 5 months. While treatment with yttrium-90 (90Y) radioembolization alone may improve outcomes, overall prognosis remains poor. We hypothesize that the combination of 90Y radioembolization to the parenchymal component of the tumor and stereotactic body radiation therapy (SBRT) to the vascular component is a safe and effective means of improving outcomes. Materials and Methods: A single center retrospective review identified 12 patients with cancers involving the liver who received both 90Y radioembolization and SBRT to the PVTT between May 2015 to August 2020. Primary endpoint was the 90-day toxicity rate by the Common Terminology Criteria for Adverse Events version 5.0. Secondary endpoints were the best response rate based on the Response Evaluation Criteria in Solid Tumors v1.1, local control rate, portal vein (PV) patency rate, and median OS. Results: Patients received a median 90Y dose of 104.3 Gy (range, 83.3 to 131.7 Gy) and a median 5-fraction SBRT dose of 32.5 Gy (range, 27.5 to 50 Gy). There were no late toxicities reported, and only 7 acute grade 1 toxicities reported: elevation of liver function tests (17%), nausea (17%), fatigue (17%), and esophagitis (8%). Local control was 83%. 58% of patients had a patent PV after treatment. With a median follow-up time of 28 months, 1-year OS was 55% with a median OS of 14 months. Conclusion Combination 90Y radioembolization and SBRT appears to be safe and effective in the treatment of PVTT. Larger prospective studies are warranted to better evaluate this combination treatment approach.