RESUMEN
Hepatitis B is a disease that is preventable with vaccination. Antibody levels after vaccination may be affected by suppression of the immune system due to cancer therapy. Children with cancer have a high risk of hepatitis B virus [HBV] infection. We aimed to assess the pretreatment immunization status against HBV infection and the rate of continuity of immunization after therapy in children with cancer. Retrospective case review of patients treated from 2004 to 2008. We reviewed the medical records of patients treated in the departments of pediatric hematology and oncology and collected data on immunization history and hepatitis B serology. Anti-HBs antibody titers were compared before and after treatment. This study included 159 [99 males, 60 females] children who had a serologic examination. Antineoplastic therapy had been given for acute leukemia [n=66], non-Hodgkin lymphoma [n=27], Hodgkin lymphoma [n=20], and solid tumors [n=46]. Fifty-one patients had not been immunized against HBV prior to the therapy; HBV serology was negative in 49 of these patients and HBsAg was positive in 2 patients. Anti-HBs antibody positivity was present in 99 of 108 patients with an immunization history, whereas no vaccination response was present in 9 patients. The titer of anti-HBs antibody was decreased below the protection level in 33 [33%] patients with positive anti-HBs antibody, whereas the protection level was found to be maintained in 66 [67%] patients. The most significant decrease [63.6%] was observed in leukemia patients. Posttreatment HBsAg and HBV DMA positivity was detected in two of the patients with negative pretreatment serology, whereas no HBV infection developed in the group with positive anti-HBs antibody. This study demonstrated the importance of routine childhood vaccination in reducing the risk of HBV infection in patients with cancer