TAF to Prevent HBV Reactivation in Cancer Patients

This prospective single arm study would be conducted in Taiwan. Patients who fulfill the inclusion criteria, will receive TAF before the initiation of systemic chemotherapy. Based on the guidance of NHI in Taiwan, prophylactic anti-viral agent should be prescribed within 7 days before chemotherapy and would be discontinued at 6 months after cessation of chemotherapy. The duration of TAF prophylaxis would be followed the guidance of NHI in Taiwan, however, the end of our observation would be at week 48 after TAF use. Patients will receive regular follow up at week 4, 12, 24, 36 and 48 (for T-bil, AST, ALT, creatinine, HBsAg, HBV DNA) till 1 year and the outcome will be collected. Platelet and HBcrAg would be examined at enrollment, 24 weeks and 48 weeks. HBeAg and anti-HBeAg will be examined at enrollment and 48 weeks.