Heavier and taller children may be more likely to develop kidney cancer as adults, a Danish study suggests.
Experts found the greatest risks for children who had normal weight at age seven but who were overweight by age 13.
Researchers already know that about one-third of kidney cancer cases are preventable, with obesity linked to 24% of cases.
For the study, led by experts at the Danish Center for Research and Clinical Prevention at Bispebjerg and Frederiksberg Hospital, data from 301,422 people – half of whom were men – were examined.
All were born from 1930 to 1985 and had their weight and height recorded in annual school health examinations between the ages of seven and 13 years.
Cases of renal cancer were then identified from the Danish Cancer Registry and the risk of the disease was calculated.
During an average follow-up of 32 years, 1,010 individuals were diagnosed with renal cancer.
Experts found that in a pair of boys 13 years of similar height, where one was 5.9 kg heavier, the heaviest boy had a 14% increase in the risk of kidney cancer compared to the lighter child.
The same happened with a pair of 13-year-old girls, where the heaviest girl was 6.8 kg.
When the time came, a 13-year-old boy who was 8 inches taller than his partner had a 12 percent increase in the risk of kidney cancer in later life.
The same happened with a pair of girls where the highest was 6.9 centimeters higher.
Compared to normal weight children at age 7 and 13, children who were overweight at both ages did not have a higher risk of kidney cancer.
But children who were normal weight at age seven and overweight at age 13 had a 67 percent greater risk of developing the disease.
The study was presented at the European Congress on Obesity in Glasgow and was reviewed by conference staff.
Lead author Dr. Britt Wang Jensen said: "We know that overweight in adulthood is associated with an increased risk of renal cell carcinoma (RCC).
"We also know that cancers take many years to develop, so we have a theory that overweight in childhood would increase the risk of RCC later in life.
"We found in other studies that childhood height is positively associated with various forms of cancer.
"So we expected to find that taller kids are at a higher risk of RCC than average children."
Australian Associated Press