Study Links Childhood Obesity to Increased Bladder Cancer Risk

London: Adults who were overweight in childhood may be at greater risk of developing bladder cancer, according to a new study.

Published in the journal Annals of Human Biology, the study based on more than 315,000 children in Denmark, shows body size is associated with getting the disease later in life. A body mass index (BMI) increase above average during childhood, high/low birth weight, and below-average height also increase the odds. Identifying causes that arise early on could lead to a new understanding of the disease which is the 9th most common cancer in the world, has high recurrence rates, and is more likely to affect men aged over 65, the study said.

"These results suggest that the higher levels of overweight and obesity in children today may contribute to an increased burden of bladder cancer in future," said lead author Dr. Kathrine K Sorensen from Bispebjerg and Frederiksberg Hospital in Denmark.

"Our study contributes to the understanding of how body size early in life may indicate a risk for bladder cancer," Sorensen added.

The link between bladder cancer and lifestyle factors such as obesity is already established. However, little is known about whether this association has its origin in childhood. The findings were based on information relating to 315,763 children born between 1930 and 1989, and aged from seven to 13.

This data from the Copenhagen School Health Records Register included BMI, birth weight, and height, and was cross-referenced with the Danish Cancer Registry. The number of individuals diagnosed with bladder cancer as adults were 1,145, including 839 men.

The risk of developing the disease later in life was, for example, 10 percent higher for a 13-year-old boy of average height (154.5 cm or 5ft) whose BMI increased 5.9kg above normal (the equivalent of 42.5kg). Conversely, a boy the same age and 8cm taller than average (162.5 cm or 5ft 3ins) had a six percent lower risk of being diagnosed, according to the research.

"To put our results in perspective, for two 13-year-old boys of average height (154.5 cm), moving from a weight of 42.5 kg to 48.4kg equates to a 10 percent higher risk of bladder cancer in the heavier boy," said senior author Dr. Jennifer L Baker.