CHANGE IN IMMUNOLOGICAL MEMORY OF HEPATITIS B VACCINE AFTER CHEMOTHERAPY; A REAL PROBLEM IN PEDIATRIC CANCER PATIENTS.

Background:-Children with cancer are at risk of Hepatitis B virus infections as a result of recurrent blood transfusions and also due to suppressed immune system. The national immunization program plays an important role in decreasing hepatitis B infection in children with cancer; however, the efficacy of the immunization strategies is questionable. We aimed at evaluating the acquired immunity from previous hepatitis B vaccination in cancer patients after recovery of their immune system. Patients and Methods:- Case control study was conducted on 22 patients with cancer(13 males,9 females, mean age 7.2±3.14 years) who completed their standard chemotherapy at least 6 months prior to the study. Twenty two age and sex matched healthy children were enrolled as a control group. HBsAb and HBcAb concentrations were determined in the studied subject's serum by ELISA. Results:- The frequency of non immune subjects in children with cancer was significantly higher than those in healthy children (P-value=0.001), where anti-HBs antibody titer was more than 10 mIU/ml in 54.5% of patients and less than 10 mIU/ml in 45.5% of patients. While in healthy controls, 90.9% had antibody titer more than10 mIU/ml and 9.1% had antibody titer less than 10mIU/ml. No significant relation was found between loss of immunity against HBV and age of patient, type of cancer and duration of chemotherapy. Conclusion:-Children with cancer are at increased risk for HBV infection. HBV revaccination should be considered at least six month post chemotherapy.