Smith M A, Simon R, Strickler H D, McQuillan G, Ries L A, Linet M S
National Cancer Institute, Division of Cancer Treatment and Diagnosis, Bethesda, MD 20892, USA.
Cancer Causes Control. 1998 May;9(3):285-98. doi: 10.1023/a:1008873103921.
The incidence of acute lymphoblastic leukemia (ALL) in children has shown temporal and geographic variation during the 20th century, with higher rates in developed nations appearing in the first half of the century, but with persisting low rates in developing nations. We sought to assess the relation of childhood ALL with hygiene conditions, an aspect of socioeconomic development affecting rates of exposure to infectious agents.
Infection patterns for hepatitis A virus (HAV), an agent with a fecal-oral route of transmission, were used to indicate hygiene conditions in different populations, with emphasis on instructive United States and Japanese data. A catalytic model was fit to these data, estimating the HAV force of infection and age-specific seroprevalence rates over time. These analyses were used to assess the temporal relationship of changes in HAV infection rates to changes in childhood leukemia mortality and incidence rates.
We observed an inverse relationship between HAV infection prevalence and rates of childhood leukemia. Further, decreases in the HAV force of infection in the United States and Japan appear to have preceded increases in childhood leukemia rates. We describe a model based on a putative leukemia-inducing agent with a change in infection rate over time correlated with that of HAV that describes well the temporal trends in childhood leukemia rates for White children in the US and for Japanese children.
The data suggest that improved public hygiene conditions, as measured by decreased prevalence of HAV infection, are associated with higher childhood ALL incidence rates. The model that we present supports the plausibility of the hypothesis that decreased childhood exposure to a leukemia-inducing agent associated with hygiene conditions leads to higher rates of ALL in children by increasing the frequency of in utero transmission caused by primary infection during pregnancy (or by increasing the number of individuals infected in early infancy because of lack of protective maternal antibodies).
20世纪期间，儿童急性淋巴细胞白血病（ALL）的发病率呈现出时间和地域差异，发达国家在本世纪上半叶发病率较高，而发展中国家的发病率一直较低。我们试图评估儿童ALL与卫生条件之间的关系，卫生条件是社会经济发展的一个方面，会影响接触传染源的几率。
甲型肝炎病毒（HAV）通过粪-口途径传播，利用其感染模式来表明不同人群的卫生条件，重点参考具有指导意义的美国和日本的数据。采用催化模型拟合这些数据，估计HAV的感染强度以及随时间变化的年龄特异性血清阳性率。这些分析用于评估HAV感染率变化与儿童白血病死亡率和发病率变化之间的时间关系。
我们观察到HAV感染流行率与儿童白血病发病率之间呈负相关。此外，美国和日本HAV感染强度的下降似乎早于儿童白血病发病率的上升。我们描述了一个基于假定白血病诱导因子的模型，该因子的感染率随时间变化与HAV的感染率相关，该模型很好地描述了美国白人儿童和日本儿童白血病发病率的时间趋势。
数据表明，以HAV感染流行率下降衡量的公共卫生条件改善与儿童ALL发病率较高相关。我们提出的模型支持以下假设的合理性：儿童接触与卫生条件相关的白血病诱导因子减少，通过增加孕期初次感染导致的宫内传播频率（或由于缺乏母体保护性抗体而增加婴儿早期感染的个体数量），从而导致儿童ALL发病率升高。
