Epstein-Barr Virus Reactivation and the Effect of EGCG on Virus Reactivation in Remission Patients

Inclusion Criteria: * Histologically proven NPC. * 2010 AJCC stage II-IVB. * Age ≧ 20 years old. * Performance status of ECOG ≦ 2. * Finished RT ≧66 Gy within 6 months (± induction/concurrent/adjuvant chemotherapy). * Clinical complete remission by re-staging work-ups within 3 months before entry. * Plasma EBV DNA = 0 copy/ml within 4 weeks before entry. * Adequate liver, renal, and bone marrow function:Serum total bilirubin level ≦ 2.5 mg/dl. Serum creatinine ≦ 1.6 mg/dl. WBC ≧ 3,000/ul. Platelet count ≧ 100,000/ul. * No intake of EGCG or similar dietary supplements. * Signed informed consent. * No further anti-cancer treatment. Exclusion Criteria: * Occurrence of locoregional recurrence or distant metastasis. * Inadequate RT or finishing RT \> 6 months. * Not complete remission by re-staging work-ups within 3 months before entry. * Plasma EBV DNA \> 0 copy/ml within 4 weeks before entry. * Intake of EGCG or similar dietary supplements during recent 3 months. * Severe cardiopulmonary diseases (unstable angina and/or congestive heart failure or peripheral vascular disease requiring hospitalization within the last 12 months; chronic obstructive pulmonary disease exacerbation other respiratory illness requiring hospitalization) or clinically significant psychiatric disorders.