Mortality among Inhabitants of an HTLV‐I Endemic Area in Japan

Abstract

A community‐based cohort study was conducted to clarify the risk of human T‐cell leukemia virus type I (HTLV‐I) infection for cause‐specific deaths. A total of 1,997 individuals (751 men and 1,246 women) aged 30 or older in A‐IsIand, Nagasaki Prefecture, Japan who had voluntarily attended annual mass health examinations, including serum HTLV‐I antibody test, were followed up for a mean period of 5.3 years. In a Cox proportional hazards analysis adjusted for age at baseline, the HTLV‐I seropositivity was found to be associated with mortality from all causes in men (hazard ratio (HR) 1.89; 95% confidence interval (CD 1.01–3.54) and women (HR 1.94; 95% CI 1.16–3.22). When the effects of 2 deaths (1 man and 1 woman) from adult T‐cell leukemia/lymphoma (ATL) were excluded, the mortality risk decreased slightly but was still significantly or marginally significantly greater than 1 in both men (HR 1.77; 95% CI 0.93–3.37) and women (HR 1.87; 95% CI 1.12–3.12). Further analysis of cause‐specific deaths revealed a significant increase in the risk for non‐neoplastic diseases but not for neoplasms excluding ATL. These findings suggest that long‐term HTLV‐I infection represents a health hazard greater than just that for the development of ATL. It was difficult, however, to draw a conclusion regarding the association between HTLV‐I infection and cancer risk, because the number of cancer deaths was small and the incidence of cancer was not investigated.

Human T Lymphotropic Virus Type 1 Infection and Gastric Cancer Development in Japan

“…Iwata et al [7] reported that the hazard ratio associated with HTLV-1 infection for death from all causes, excluding ATL, was 1.77 (95% CI, 0.93-3.37) for males and 1.87 (95% CI, 1.12-3.12) for females, although analysis of cause-specific mortality revealed a significantly increased risk for nonneoplastic disease in each group. Arisawa et al [2] reported that HTLV-1-seropositivity was associated with increased mortality from all causes, excluding ATL (risk ratio [RR], 1.3; 95% CI, 1.0 -1.7), and that HTLV-1 infection was not associated with an increased risk of any cancer other than ATL, colorectal cancer, liver cancer, and lung cancer but was associated with a reduced risk of gastric cancer (RR, 0.42; 95% CI, 0.17-0.99).…”

Human T‐Lymphotropic Virus Type‐I Infection, Antibody Titers and Cause‐specific Mortality among Atomic‐bomb Survivors

“…12) In addition, it is noteworthy that there was a significant dose-response relationship between the antibody titer, a correlate of HTLV-I proviral load, 13,14) and mortality rate. The findings from the present study may support the idea that HTLV-I infection exerts an adverse effect on mortality which is greater than that caused only by the development of ATL.…”

“…In our previous cohort study performed at A-Island, an HTLV-I endemic area of Nagasaki, Japan, HTLV-I seropositivity was associated with an approximately 1.8-1.9-fold increased risk of mortality, even after the effect of ATL was excluded. 12) However, the small number of deaths precluded detailed analysis of cause-specific mortality, and the generalizability of the results remained unclear.…”

Evaluation of adult T-cell leukemia/lymphoma incidence and its impact on non-Hodgkin lymphoma incidence in southwestern Japan

“…Several epidemiologic studies have reported the mortality rates, incidence rates and the cumulative risks of ATL among HTLV-I carriers in various countries in the world (Tajima et al, 1987;Murphy et al, 1989;Tokudome et al, 1989;Kondo et al, 1989;Iwata et al, 1994;Cleghorn et al, 1995;Gerard et al, 1995). However, most of the earlier studies on the incidence rates were based on seroprevalence data from only a small proportion of the population examined or from voluntary blood donors.…”