Modelling the risk of adult T‐cell leukemia/lymphoma in persons infected with human T‐lymphotropic virus type I

Evidence is provided in support of the hypothesis that childhood infection with HTLV‐I is important to the development of ATL and diseases with shorter latent periods, such as tropical spastic paraparesis, should have a higher incidence in adult females than in adult males.

Abstract

Adult T-cell leukemia/lymphoma (ATL), a malignancy of mature CD4-positive lymphocytes, has been etiologically linked to the human retrovirus HTLV-I. Although a long latent period is suggested from migrant studies, little prospective information on the risk of developing ATL among persons with HTLV-I infection is available. We present here a model for ATL risk based upon age- and sex-specific HTLV-I seroprevalence data from a cross-sectional survey of 13,000 Jamaicans and ATL incidence data from a 2 1/2-year case-control study. By examining the age-specific incidence of ATL relative to both adult and childhood-acquired seropositivity versus childhood-acquired seropositivity alone, we provide evidence in support of the hypothesis that childhood infection with HTLV-I is important to the development of ATL. Using this model, the cumulative lifetime risk of ATL for those infected before age 20 is estimated to be 4.0% for males and 4.2% for females. Under this hypothesis, HTLV-I-associated diseases with shorter latent periods, such as tropical spastic paraparesis, should have a higher incidence in adult females than in adult males.