The proposed study is an open-label, single-center, single arm phase 1b study to evaluate the safety and efficacy of radiotherapy plus sintilimab for HCC with PVTT.

The patients were divided into two groups. The first group: the single dose of radiotherapy was 200 cGy, once a day, the total dose was 5000 cGy. The second group: the single dose of radiotherapy was 300 cGy, once a day, and the total dose was 3000 cGy.

Inclusion Criteria:

1. Ability to understand and willingness to sign a written informed consent document.
2. Locally advanced hepatocellular carcinoma with identified tumor thrombosis of main portal vein or primary branches (left and / or right branches)
3. Has at least 1 measurable lesion
4. Age ≥18 years
5. Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1
6. Adequate organ function
7. Child Pugh class A
8. Life expectancy ≥12 weeks.
9. Antiviral therapy per local standard of care for hepatitis B
10. Woman of child bearing potential must have a negative pregnancy test
11. Must use acceptable form of birth control while on study

Exclusion Criteria:

1. Has previously been performed by raditotherapy for the area to be treated.
2. With extrahepatic metastasis
3. History of hepatic encephalopathy or liver transplantation
4. Untreated hepatitis infection: HBV DNA>2000IU/mlor10000 copy/ml, HCV RNA> 1000copy/ml, both HbsAg and anti-HCV body are positive
5. Has liver tumor not amenable to radiotherapy, or has had prior upper abdominal radiation therapy within planned volumes
6. Has had esophageal or gastric variceal bleeding within 3 months prior to study enrollment
7. With serious systemic diseases such as heart disease and cerebrovascular disease, and the condition is unstable or uncontrollable
8. Evidence of active pulmonary tuberculosis (TB)
9. Positive test of immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS)
10. History of allergic reactions to related drugs