Abstract
AIM: To estimate hepatitis B virus (HBV) infection testing rate in cancer patients before chemotherapy with a focus on HBV reactivation. METHODS: A retrospective study was conducted from January 1, 2009 to June 30, 2010. Inclusion required that patients be naïve to cancer chemotherapy but have indications for it. Patients who did not receive chemotherapy for any reason were excluded. Important clinical information, such as the levels of HBV DNA and serological markers were collected. HBV reactivation was defined as an increase in serum HBV DNA to > 1 log higher than that of the pre-exacerbation baseline, or serum HBV DNA conversion from negative to positive. HBV DNA levels > 1000 copies/mL were defined as HBV DNA positive. The χ² or Fisher's exact test was used for analysis of categorized data. Multiple logistic regression analysis was used to estimate the odd ratio and 95%CI of the HBV screening rate. RESULTS: Of 6646 patients, 5616 (84.5%) received chemotherapy. Only 17.1% of the cancer patients received pre-chemotherapy HBV testing (43.2% for hematological malignancies and 14.9% for solid tumors). Patients who had received rituximab therapy, had elevated aminotransferase levels, or had hematological malignancies were more likely to receive HBV testing. The prevalence of hepatitis B surface antigen (HBsAg) positivity was 13.4%. HBV reactivation (appearance of HBV DNA or an increase in HBV DNA levels by 1 log₁₀ was observed in 33.1% (53/160) of the patients after chemotherapy. Among patients without prophylactic antiviral therapy, the reactivation rate was 43.9% (43/98) in the solid tumor group. Two reactivation cases occurred in patients who were HBsAg negative, but positive for hepatitis B core antibody. HBV reactivation was more likely to occur in patients with lymphoma, high levels of HBV DNA, or hepatitis B e antigen, and in men. CONCLUSION: Less than 20% of patients received HBV testing before chemotherapy. HBV reactivation would have occurred in about 50% of infected patients with solid tumors without antiviral prophylaxis.