Heavier and taller children are more likely to develop kidney cancer as adults than their average-sized peers, warn researchers.

"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. We therefore had a theory that already being overweight in childhood would increase the risk of RCC later in life," said lead author Britt Wang Jensen from Bispebjerg and Frederiksberg Hospital in Denmark.

RCC is the most common form of kidney cancer found in adults. For the study, the researchers included 301,422 individuals from the Copenhagen School Health Records Register born from 1930 to1985. The weights and heights were measured at the ages seven to 13 years, and body mass index (BMI) was used to categorise the children as normal-weight or overweight, suggested by the International Obesity Task Force.

During a median of 32 years of observation, 1,010 individuals (680 men) were diagnosed with RCC. Among men and women, significant and positive associations were observed between childhood BMI and height, respectively, and RCC risk.

Children who grew from average to above average height had an eight per cent increased risk of RCC, the study said. "Our findings that heavier and taller children have increased risks of RCC open the door to new ways to explore the causes of kidney cancer," Jensen said. The study was presented at the European Congress on Obesity being held in Glasgow, Scotland from April 28 to May 1.