New research from the International Childhood Cancer Cohort Consortium (I4C) confirms that childhood cancer occurrences rises with increasing birthweight, but shows that this is unlikely to be primarily due to a mother’s weight gain during pregnancy – an important contributor to size of the baby. The finding is believed to be an important step toward eventually understanding how to prevent childhood cancer. The study was recently published in the journal Paediatric and Perinatal Epidemiology.
The study was the first designed to specifically collect data before the children developed cancer. It includes pooled data on infant and parental characteristics and cancer incidence, covered 380,000 live births. It was collected from studies going back more than 50 years from six geographically diverse regions, including the UK, USA, Denmark, Israel, Norway and Australia. The total analysis included 377 children with cancer, including 115 with leukaemia and 262 with non-leukaemia-type cancers.
“We have been able to compile a significant amount of evidence that effectively shows that childhood cancer incidence rises with increasing birthweight,” said Professor Terry Dwyer, the Executive Director for The George Institute for Global Health. “While we observed a correlation between increased birthweight and higher risk of cancer incidence in children, there were no significant interactions with maternal pre-pregnancy overweight or pregnancy weight gain.”
The study showed that after adjusting for gestational age and sex an increased risk of 26 percent for every kilogram increase in birthweight was observed for all cancers. In older children (diagnosed at or after three years of age), cancers other than leukaemia are particularly related to high birthweight.
“At The George Institute we are focused on the prevention, treatment and care of noncommunicable diseases, like cancer,” said Professor Dwyer. “I am more optimistic that we’ll find ways of preventing childhood cancer than I was when we started this study 10 years ago. We know that there are no easy answers, but we are assembling more clues, like this piece of evidence, which will help us fill in the puzzle. Additional research into childhood cancer is needed so that we can provide actionable solutions to improve outcomes for future generations.”
I4C researchers plan to follow this study up with several lines of inquiry, including: looking at data in new cohorts such as in Japan and China to see whether this association exists there as well; investigating other factors that have some relationship to birth weight, such as birth order, to see whether the association is similar in infants of different birth order; and making cord blood measurements from infants in the cohorts to determine whether growth hormones of various types explain what we have found.
Dwyer, a Professor of Epidemiology at the Oxford Martin School and the Nuffield Dept. of Population Health, also leads the I4C, an international alliance of longitudinal studies of children. The I4C aims to make major contributions in advancing understanding of the role of early-life exposures in childhood cancers.
While previous studies have posited on the connection between childhood cancers and high birthweights, the collaboration of the six cohorts has allowed the examination of a wider range of potential factors measured prospectively including maternal age, marital status, education level, smoking propensity, previous live births, diabetes, pre-pregnancy BMI and total pregnancy weight gain.
Researchers used state-of-the-art statistical techniques to analyse the complex data set. The final dataset excluded multiple births due to higher rates of low birthweight and children with Down syndrome due to previously observed higher risks of childhood leukaemia.
Source: George Institute