Risk factors for paediatric HIV malignancies

A paper published in JAMA reported findings from a study designed to identify risk factors for malignancy among HIV-positive children.

This multicentre case-controlled study evaluated 43 children with a new malignancy and 74 children without a malignancy based on the duration of their HIV infection. The children were enrolled between January 1992 and July 1998.

Possible risk factors assessed included: demographic characteristics, HIV characteristics, previous antiretroviral treatment and CD4 cell count. Coviral infections with Epstein-Barr virus (EBV), cytomegalovirus (CMV) and human herpes virus 6 were assessed by semiquantative polymerase chain reaction (PCR) assays and serological testing.

Malignancy diagnoses included 28 cases of non-Hodgkin lymphoma, four B-cell acute lymphoblasic leukemia, one Hodgkin disease, eight leiomyosarcoma, one hepatoblastoma and one schwannoma.

The investigators reported that for children with CD4 counts of ≥200 cells /mm3, EBV viral load of greater than 50 viral genome copies per 105 peripheral blood mononuclear cells (PBMC) was strongly associated with cancer risk (p<0.001) but there was no association for children with CD4 counts of <200 cells (p=0.99). They also found that ZDV antiretroviral therapy offered no significant protective effect against malignancies for either the high or low CD4 groups. Additionally route of HIV infection was not associated with increased cancer risk.

They added: “The pathogenesis of HIV-related paediatric malignancies remains unclear and other contributing risk factors can be elucidated only through further study.”

Comment

Malignancies in children have always been a relatively rare complication of HIV infection. They accounted for less than 2% of AIDS-defining illnesses in the early natural history studies, presumably because children were dying of other complications before malignancies manifested themselves.

Clearly this cohort was mostly enrolled pre-HAART. We are seeing very few new malignancies in children on HAART, but need to remain vigilant, as they do still occur. In addition, in children of families from sub-Saharan Africa, the incidence of Kaposi’s sarcoma is increasing.