Prophylactic or Preemptive Entecavir in Patients With Gastrointestinal Cancer Who Are Inactive Hepatitis B Carriers

Prior treatment

• Prior HBV reactivation
• Received anti-HBV therapy for chronic hepatitis B within 6 months before enrollment
• Scheduled hepatic radiotherapy or radioisotope therapy
• Patients with immunodeficiency, other congenital or acquired immunodeficiency, or transplantation history
• According to the investigators' judgment, patients with concomitant disease that seriously harms patients' safety or the completion of study.

Other illness

• History of liver cirrhosis
• Active co-infection with other hepatitis viruses
• HIV infection
• Autoimmune hepatitis
• History of hepatic radiotherapy
• Patients with a history of psychiatric drugs abuse and can't quit or with a mental disorder

Other

• Pregnant or lactating women

• Patients with age between 18 and 75
• Patient with histology-proven locally advanced unresectable or metastatic gastrointestinal cancers (colorectal cancer, gastric cancer, esophageal cancer, hepatocellular carcinoma, pancreatic cancer, and cholangiocarcinoma)
• Planned to receive first-, second-, or third-line anti-tumor therapy (chemotherapy or PD-1/PD-L1 monoclonal antibody immunotherapy)
• Patients with Eastern Cooperative Oncology Group performance status (ECOG) of 0-2
• Patients planned for at least 4 cycles of chemotherapy or immunotherapy
• Patients with at least 6 months' life expectancy from date of recruitment
• Patients with chronic or past HBV infection (HBsAg-positive or HBcAb-positive), and hepatitis B is inactive
• Patients with normal liver function tests including alanine aminotransferase (ALT), aspartate aminotransferase alkaline (AST), and bilirubin
• Patients with negative HBV-DNA
• Adequate major organ function (laboratory tests 14 days before randomization meeting requirements for anti-tumor therapy)
• Patients who sign the informed consent
• Patients with good compliance during chemotherapy and follow-ups.