The rate of hepatitis B and C virus infections and the importance of HBV vaccination in children with acute lymphoblastic leukemia

Aim:  The aim of the study was to evaluate the rate of hepatitis B and C virus infection and emphasize the importance of hepatitis B virus (HBV) vaccination in leukemic children.


INTRODUCTION
H EPATITIS WITH ELEVATION of aminotransferase levels is common during the treatment of children with acute lymphoblastic leukemia (ALL). Toxic hepatitis may result from chemotherapeutic agents, especially methotrexate (Mtx) and 6-Merkaptopurine . In addition to chemotherapy, hepatitis B and C virus infections, occasionally leukemic infiltration, bacterial infections and antibiotics used during febril neutropenia periods, are also responsible for the elevation of hepatic transaminases. Hepatitis B virus (HBV) and hepatitis C virus (HCV) infections are more common in children with ALL than in the general population because of transfusions given during the treatment and the immunosuppressive effect of the chemotherapy. [1][2][3] The aim of this study was to evaluate the hepatitis B or C virus infections of children treated for ALL in our center and to emphasize the importance of HBV vaccination in leukemic children. anti-hepatitis B surface antibody (anti-HBs), antihepatitis B core antibodies (anti-HBc), and antihepatitis C antibody (anti-HCV) were studied by the ELISA method (Axsym Diagnostics, Abbott Park, IL). Hepatitis C virus RNA in serum and plasma was detected by PCR assay (TaqMan; Perkin Elmer/Applied Biosystems, Foster City, CA). Serological markers for HBV and HCV and liver function tests were performed at diagnosis and at 3-month intervals during the followup period. Children seronegative for HBV were vaccinated according to our institutional vaccination protocol. 7 Serological markers for HBV were repeated six weeks after the vaccination. Anti-HBs >10 IU/L was defined as a protective antibody level.

B ETWEEN MARCH 1991 and
Serum transaminase elevation >300 IU/L was accepted as severe toxic hepatitis, 8 and serum transaminase elevation was also detected in viral hepatitis. We performed the differential diagnosis of toxic and viral hepatitis as follows: negative serological markers for HBV and HCV associated with elevated transaminases during chemotherapy suggested a diagnosis of toxic hepatitis. If cessation of chemotherapy resulted in a gradual drop in the elevated transaminases, this was diagnostic for toxic hepatitis. However, in the cases of viral hepatitis, positive serological markers for HBV or HCV and elevated transaminases, especially alanine aminotransferase (ALT) elevation, were both necessary for the diagnosis. ALT is highly liver-specific, whereas aspartate aminotransferase (AST) can also be elevated after injury to other organs. Marked increases in aminotransferase activities, especially ALT elevation, best reflect the degree of liver cell injury. After the diagnosis of viral hepatitis had been established, cessation of chemotherapy was not enough for transaminases to return to normal.
The diagnosis of acute hepatitis B is based on the detection of HBsAg and AntiHBc-IgM. During the initial phase of infection, the markers of HBV replication (HBe Ag and HBV-DNA) were also present. Past HBV infection was diagnosed by the detection of anti-HBs and AntiHBc-IgG. Immunity to HBV infection after vaccination was determined by the presence of anti-HBs only. The diagnosis of chronic HBV infection was based on the detection of HBsAg. Additional tests for HBV replication (HBe Ag and HBV-DNA) were also present to determine if the patient should be considered for antiviral therapy. HbsAg-positive, but HBV replication markers (HBe Ag and HBV-DNA) negative individuals were described as inactive HbsAg carriers. If positive serological markers for HBV and HCV had persisted for more than six months, the diagnoses of chronic hepatitis B and C infections were established.
Additionally, liver biopsy was performed to confirm the diagnosis of chronic hepatitis B and C infections. Histopathological confirmation of the diagnosis was established, especially before the beginning of antiviral treatment including lamivudine and interferon therapies. Since 10 of the 24 patients with HBV infection and all three with HCV infection developed chronic hepatitis B and C infections, they underwent liver biopsy and received antiviral treatment.
Statistical analysis was performed with a statistical package program, SPSS for Windows, version 10.0 (SPSS Inc., Chicago, IL). The χ 2 -test was used to compare the patients with different risk and chemotherapy groups. The rate of the patients who received St Jude Total XI and St Jude Total XIII protocols were compared in respect to the development of toxic hepatitis, HBV and  Thus the majority of patients with HBV and HCV infections (23/27, 85.2%) had HR protocols (P < 0.001) ( Table 1).

A MONG
All of the donors were negative for the serological markers of HBV, HCV and HIV and all of the patients were transfused from the same blood bank in Hacettepe University Faculty of Medicine. Retrospective chart review of the patients revealed that the HR patients received 8.5 ± 2.3 times eritrocyte and 6.5 ± 2.2 times platelet transfusions, whereas LR patients received 4.5 ± 2.2 times eritrocyte and 3.4 ± 2.0 times platelet transfusions during the treatment. The differences between eritrocyte and platelet requirements of the HR and LR groups were statistically significant (P < 0.001).
Fourteen of 29 patients with toxic hepatitis had St Jude Total XI protocol (six LR and eight HR) and 15 patients had St Jude Total XIII protocol (14 LR and one HR). Most of the patients with toxic hepatitis (20/29, 68.9%) had LR protocol, especially St Jude Total XIII LR protocol (P < 0.05) ( Table 1). The mean AST level was 388 ± 284 U/L (range: 332-1012) and ALT level was 424 ± 316 U/L (range: 310-900) in patients with toxic hepatitis. After cessation of chemotherapy, the high AST and ALT levels were decreased to normal levels in all of the patients with toxic hepatitis.

DISCUSSION
H EPATITIS REVEALED BY a marked transaminase elevation may be seen in patients with leukemia. [8][9][10][11] Especially, HBV and HCV infections may cause viral hepatitis in leukemic children who are heavily transfused after the onset of their hematological disease. In developing countries where HBV and HCV infections are common in the general population of the country, such as Turkey, children with ALL will be at a greater risk for HBV and HCV infections. In Turkey the prevalence of HBV infection is put at 5.4-8.2% in different nationwide surveys. 12,13 The prevalence of HBV infection in our study (15.0%) is higher than that of the general population in the country. However, it has been reported in different studies from Turkey that the prevalence of HCV infection is 0.5-2.4% and in our study the prevalence of HCV infection is 1.5%, which is almost equal to that of the general population in our country. 14, 15 Kocabas et al. 16 reported that HBV and HCV © 2007 The Japan Society of Hepatology infections are also common among Turkish children with cancer. In that study, 47.4% of the patients with cancer were positive for HbsAg and anti-HCV was detected in 5.8% of the cancer patients.
Toxic hepatitis is also common during combined chemotherapy, including methotrexate (Mtx) and 6mercaptopurine (6-MP). Pharmacodynamic and pharmacogenetic properties of the patients may be responsible for the development of toxic hepatitis. Several studies have been performed to understand the mechanism of toxic hepatitis induced by these drugs. Methotrexate and its polyglutamates, 6-thioguanine nucleotides (the major cytotoxic metabolites of 6-MP) and methylated metabolites of 6-MP generated by thiopurine methyltransferase in competition with the formation of 6-thioguanine nucleotides were postulated to be responsible for toxic hepatitis in children with ALL. [1][2][3][8][9][10][11] Berkovitch et al. 2 conducted a study related to the toxic hepatitis of 6-MP in childhood ALL. In that study, they found that the time to achieve peak 6-MP levels was significantly longer in the symptomatic patients with toxic hepatitis compared to the asymptomatic patients. These results suggest the accumulation of 6-MP and its metabolites in the liver of the patients with gastrointestinal symptoms, leading to toxic hepatitis. 2 In our study, the majority of patients with HBV or HCV infections had HR protocols, whereas most of the patients with toxic hepatitis had LR protocol, especially St Jude Total XIII LR protocol.
Hepatotoxic agents were equal for St Jude Total XI-LR and HR protocols except cranial radiotherapy in St Jude Total XI-HR protocol. 4,5 However, St Jude Total XIII-LR protocol was based on consecutive administration of Mtx and 6-MP. St Jude Total XIII-HR protocol includes these drugs at 4-week intervals. Thus, chemotherapyrelated hepatotoxicity was much more common in children who received St Jude Total XIII-LR protocol. 6 However, HBV or HCV infections were more common in children who received HR protocols. The children on HR protocols were more heavily transfused and immunosuppressed than the others.

CONCLUSION
I N CONCLUSION, CHEMOTHERAPY-RELATED hepatotoxicity might vary principally with the intensity of Mtx and 6-MP treatment. The effect of chemotherapy-related hepatotoxicity on the liver seems to be reversible and does not result in chronic liver disease. However, HBV and HCV infections occur on the basis of the severity of immunosuppression and the amount of administered blood products, which were much more common in HR ALL patients. Additionally, HBV or HCV infections may cause chronic hepatitis and the patients should be followed up for this respect. Periodical liver function tests and serological tests for HBV and HCV should be performed for leukemic children to monitor for these complications.