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.

During 1985 and 1986, the authors measured antibodies to human T-lymphotropic virus type I (HTLV-I) in a cohort of 13,260 Jamaicans from all parts of the island who applied for food-handling licenses. HTLV-I seroprevalence was strongly age and sex dependent, rising from 1.7% (10-19 years) to 9.1% (greater than or equal to 70 years) in men and from 1.9% (10-19 years) to 17.4% (greater than or equal to 70 years) in women. In a logistic regression analysis, women were more likely to be seropositive than were men, and farmers, laborers, and the unemployed were more likely to be HTLV-I seropositive than were those reporting student or professional occupations. In men, African ethnicity was associated with HTLV-I seropositivity in the univariate analysis but was not a risk factor after adjustment for age and sex. There was a trend toward higher age-stratified HTLV-I seroprevalence among younger women who reported more pregnancies, but older multigravidas had lower rates of HTLV-I seropositivity. Persons born outside Jamaica had significantly lower seroprevalence than did those born in Jamaica, but they were of slightly different ethnic and occupational compositions than those born in Jamaica.

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Of 95 patients consecutively diagnosed with non-Hodgkin lymphoma, 52 (55%) had antibodies to human T-cell leukemia-lymphoma virus, type I. Antibody positivity was strongly associated with skin involvement, leukemia, and hypercalcemia (p less than 0.02). Two patients had systemic opportunistic infections. Neither meningeal nor lung infiltration was detected, and lymph node infiltration was diffuse in all patients. Of 36 patients who received immunophenotypic classifications, 30 had diseases that affected the T-cell system, and the cells of all tested patients with these diseases showed the helper/inducer (T4) phenotype. Twenty-seven of these thirty-six patients were found to have adult T-cell leukemia-lymphoma, and of the 27, 24 had antibodies to HTLV-I. The median duration of survival in patients with adult T-cell leukemia-lymphoma was 17 weeks, but a subgroup of 9 patients had indolent courses and a median survival of 81 weeks, which suggests that the disease has differing expression with courses that range from smoldering and indolent to acute and rapidly fatal. Hypercalcemia was the most important prognostic determinant of adult T-cell leukemia-lymphoma.

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