Risk of cancer in children with the diagnosis immaturity at birth


Risk of cancer in children with the diagnosis immaturity at birth

Authors: Mellemkjær, Lene; Hasle, Henrik1; Gridley, Gloria2; Johansen,
Christoffer3; Kjær, Susanne K.3; Frederiksen, Kirsten3; Olsen, Jørgen

Source: Paediatric & Perinatal Epidemiology, Volume 20, Number 3,
May 2006, pp. 231-237(7)

Publisher: Blackwell Publishing

Summary Mellemkjær L, Hasle H, Gridley G, Johansen C, Kjær SK,
Frederiksen K, Olsen JH. Risk of cancer in children with the diagnosis
immaturity at birth. Paediatric and Perinatal Epidemiology 2006; 20:

Cancer risk in children born before term has been assessed in a large
number of case–control studies but very rarely in cohort studies. We
carried out a cohort study of 35 178 children with the diagnosis
immaturity at birth in the Hospital Discharge Register during 1977–89.
The children were followed for cancer in the Danish Cancer Registry
until 1994 and comparisons were made with incidence rates for all
children in Denmark. The 64 observed cases of childhood cancer in the
cohort corresponded closely to the expected number {standardised
incidence ratio (SIR) = 1.03; [95% confidence interval (CI) 0.80,
1.32]}. The only cancer site with an observed number that deviated
significantly from the expected number was central nervous system (CNS)
tumours (26 cases observed; SIR = 1.57; [95% CI 1.02, 2.30]) in
particular medulloblastoma (9 cases observed; SIR = 3.1; [95% CI 1.4,
5.9]). In a nested case–control study of the CNS tumours, we found that
more cases than controls had been exposed to diagnostic X-rays, but the
result was not significant. Surprisingly, for those born before term,
the risk of CNS tumours increased with increasing gestational age in
the nested case–control data. Our results are in line with previous
evidence that children born before term are not at increased risk for
childhood cancer in general. An explanation behind the excess of CNS
tumours could not be identified, but the effect of diagnostic X-rays in
newborns may deserve further attention.

Keywords:  childhood cancer; CNS tumours; preterm; newborn X-rays

Document Type: Research article

DOI: 10.1111/j.1365-3016.2006.00717.x

Affiliations: 1: Department of Paediatrics, Aarhus University Hospital
Skejby, Aarhus, Denmark, and 2: Biostatistics Branch, Division of
Cancer Epidemiology and Genetics, National Cancer Institute, Rockville,
MD, USA 3: Institute of Cancer Epidemiology, Danish Cancer Society,

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