Overweight children more likely to get liver cancer
Comprehensive new study finds a correlation between childhood body size during school ages and the risk of developing primary liver cancer as adults.
Liver cancer is one of the fastest-growing cancers in the world. It is also one of the deadliest forms of cancer.
Now a huge study of 285,000 Danish children shows that being overweight in childhood increases the risk of developing primary liver cancer later on in life.
This is the first time that researchers find this correlation, says the lead author of the study:
”We have long known that there was a correlation between adult obesity and the risk of developing just about all types of cancer, including liver cancer. But this is the first time that anyone finds a correlation between childhood overweight and the risk of developing primary liver cancer later on in life,” says Tina Landsvig Berentzen, a postdoc fellow at the Institute of Preventive Medicine, Bispebjerg Hospital, Denmark.
We have long known that there was a correlation between adult obesity and the risk of developing just about all types of cancer, including liver cancer. But this is the first time that anyone finds a correlation between childhood overweight and the risk of developing primary liver cancer later on in life.
Tina Landsvig Berentzen
The study is published in the Journal of Hepathology.
Study includes more than 285,000 children
The new study is based on children who went to school in Copenhagen in the period 1930-1980.
During this period, the children received annual checkups, where health professionals at the schools measured the children’s weight and height. These measurements were used to calculate the children’s Body Mass Index (BMI).
A total of 285,884 boys and girls were involved in the study.
One can easily imagine that this applies to a wide range of cancers, which provides an expanded perspective on the efforts to reduce the number of obese children.
Tina Landsvig Berentzen
Such thorough registration of school children going as far back as this study does is only possible in Scandinavia, and the Danish National Hospital Register of children’s visits to school doctors is the largest one of its kind in the world.
Less than 500 cases of liver cancer
The children were subsequently monitored via the Danish nationwide registers, including the National Cancer Registry.
Out of the more than 285,000 children covered in the study, 438 developed liver cancer later in life.
“We found 438 cases of liver cancer among our 285,000 children,” says Berentzen. “This is a very low number in a study of 285,000 persons, but the reason is that we have studied ordinary 7-13-year-old children who, fortunately, have a very small risk of developing liver cancer.”
When the researchers zoomed in on the children who did develop liver cancer, they found a clear correlation between the children’s BMI and the risk of cancer – the higher the BMI, the greater the risk.
Six kilos increase liver cancer risk by 30 percent
The researchers filtered their data for other factors that can cause liver cancer, e.g. alcohol abuse and hepatitis virus.
Even after adjusting for such factors, the correlation remained clear: the higher the children’s BMI when they were examined by school doctors and nurses, the higher their risk of having developed primary liver cancer after turning 30.
The correlation was, in fact, clear enough for the researchers to conclude that a child who weighed six kilos more than its peers had a 30-percent greater risk of developing the disease.
Obese kids end up as obese adults
Explaining this clear correlation, however, isn’t easy.
One could argue, says Berentzen, that obese children become obese adults, and this may be why they have a greater risk of developing liver cancer.
Despite making some preliminary calculations that correct for obesity in adulthood, the researchers still found a link between early obesity and the risk of developing liver cancer.
“This suggests that there is something happening in childhood that increases the risk of liver cancer independently of the weight in adulthood,” she says.
Increased risk may be caused by liver damage
The researchers are currently working from the hypothesis that childhood obesity can cause irreversible damage to the liver, so that the child from a very early age has an increased risk of liver cancer despite losing weight later on in life.
More specifically, they believe that the metabolic disorders associated with childhood obesity – e.g. pre-diabetes, fatty liver disease and chronic inflammation – can damage the liver. This damage does not disappear despite the child losing weight as it reaches adulthood, so the damage is irreversible and increases the risk of developing liver cancer.
“We also know that children’s tissue is more delicate than adult tissue. This may mean that existing damage extends to a greater extent into adulthood,” says Berentzen.
Findings may also apply to other cancers
The study of the correlation between childhood BMI and the risk of developing liver cancer is just the first in a long series of studies that look into the link between weight and growth in childhood and the risk of developing various types of cancers later in life.
Berentzen is convinced that we will be seeing more results suggesting that childhood obesity increases the risk of developing a variety of cancers later in life regardless of subsequent weight loss or weight gain.
“One can easily imagine that this applies to a wide range of cancers, which provides an expanded perspective on the efforts to reduce the number of obese children,” she says.
”In addition to the many health and social challenges that we know are associated with childhood obesity, the obesity also increases the risk of serious health problems later in life. This puts the current epidemic of obesity and the future health burden into an entirely different perspective.”
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Read the Danish version of this article at videnskab.dk
