MedicalResearch.com Interview with:
Kate A O’Neill
Department of Paediatrics
University of Oxford Children’s Hospital
John Radcliffe Hospital Oxford UK
MedicalResearch.com: What is the background for this study?
Dr. O'Neill: Cancer affects around 1 in 500 children under the age of 15. Although the diagnosis and treatment of these diseases have seen major advances over the past few decades, survivors often experience health complications later in life, and cancer remains the main cause of disease related death in children in the developed world.
The identification of risk factors for a number of adult cancers has allowed awareness and screening campaigns aimed at preventing disease. For the majority of childhood cancers, however, we still do not know what causes them, and so similar preventative measures are at present not possible.
Incidence rates for many
childhood cancers peak within the first few years of life, suggesting that the causative events occur early. For childhood leukaemia, it has even been shown that pre-malignant cells are already present at birth, indicating the disease may originate
in utero. Studies exploring potential prenatal risk factors for childhood leukaemia have consistently found that children with the disease have higher birthweights than children who do not, and it is now widely accepted that the faster a foetus grows, the higher the risk of developing leukaemia in childhood.
Leukaemia is the most common childhood cancer, accounting for approximately one third of all cases. Other childhood cancers are rarer, and it is consequently harder to perform similar risk association studies. The aim of this study was to compile information on large enough numbers of cases and controls to allow the analysis of risk associations between birthweight and all types of childhood cancer. Furthermore, we compiled data in different countries (USA and UK) to allow the comparison of results from two independent populations.
MedicalResearch.com: What are the main findings?
Dr. O'Neill: We found that with each 0.5kg (1.1lb) increase in birthweight, the risk of childhood cancer increased by 6%. Compared to babies with average birthweights (3-3.49kg, or 6.6lb -7.7lb), babies with clinically high birthweights (4kg, or 8.8lb, and above) had an increased risk of between 16% and 20%.
These increased risks were strongest for certain cancers:
- Leukaemias
- Tumours of the central nervous system
- Renal tumours
- Soft tissue sarcoma
- Neuroblastoma
- Lymphoma
- Germ cell tumours
- Malignant melanomas
Hepatic tumours showed the reverse association, with risk increasing as birthweight decreased. Retinoblastoma, an embryonal tumour, and malignant bone tumours, which occur predominantly in adolescents, did not associate with birthweight.
Our results were strikingly similar between USA and UK populations. Furthermore, birthweight appeared act independently of other factors that are known or suspected to associate with birthweight and/or childhood cancer (gestational age, birth order, plurality, maternal age and race/ethnicity).
In summary, we found that approximately half of all childhood cancers are associated with birthweight. The association with a diversity of otherwise unrelated cancers indicates that
in utero tissue growth and development has an underlying and potentially key role in the development of malignancy in childhood.
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