Am J Epidemiol 2004; 159:716-717.
Copyright © 2004 by the Johns
Hopkins Bloomberg School of Public Health
LETTERS TO THE EDITOR |
RE: "CHILDHOOD CANCER AND POPULATION MIXING"
Genetic Epidemiology Branch, National Cancer Institute, Rockville, MD 20852
In a recent article, Law et al. (1) stated that the findings of their case-control study support the Greaves hypothesis, which postulates an increased risk of childhood acute lymphoblastic leukemia (ALL) from infections delayed beyond infancy, in contrast to infections experienced in infancy, which would tend to be protective (2). Unfortunately, the authors did not provide data on the most informative group with which to assess protection resulting from early infection: children aged 1–4 years during the study period (1991–1996, though mainly 1992–1994) who were exposed to the highest numbers of recent migrants. Instead, the only results presented for specific age groups, the groups 5–9 and 10–14 years, concerned children who were mainly well past infancy in 1991. From Greaves’ hypothesis (2), one would expect that for these children, a high level of exposure to migrants would have represented a source of "delayed" infections and therefore of increased ALL risk. However, Law et al. reported increased risks of ALL in these age groups of 1.92 and 2.06, respectively, among children who were least exposed to migrants (1). Contrary to their conclusions, the findings of Law et al. for children aged 5–14 years appear to contradict Greaves’ hypothesis.
Particularly since Greaves himself was associated with this study, it is also rather surprising that his hypothesis should now be claimed as predicting protection against ALL from population mixing; previously (2) he stated that it readily accommodates the opposing effects postulated and found by Kinlen (3)—that is, excesses of childhood leukemia associated with marked population mixing in rural or isolated areas.
REFERENCES
- Law GR, Parslow RC, Roman E. Childhood cancer and population mixing. United Kingdom Childhood Cancer Study Investigators. Am J Epidemiol 2003;158:328–36.
[Abstract/Free Full Text] - Greaves MF. Aetiology of acute leukaemia. Lancet 1997;349:344–9.[CrossRef][Web of Science][Medline]
- Kinlen LJ. Epidemiological evidence for an infective basis in childhood leukaemia. (Editorial). Br J Cancer 1995;71:1–5.[Web of Science][Medline]
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  G. R. Law, R. C. Parslow, and E. Roman THE AUTHORS REPLY Am. J. Epidemiol., April 1, 2004; 159(7): 717 - 717. [Full Text] [PDF]
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