Active teenagers may be protected against the risk of deadly brain cancer, a study suggests.
People who are physically active during adolescence have 36 per cent less chance of developing the disease than those who are inactive, researchers found.
The scientists were studying glioma, the most common form of brain cancer.
Previous research had indicated that environmental influences at a time in life when the brain is developing rapidly may play a role in the disease.
The new study looked at whether markers of early life energy expenditure and intake were related to glioma risk.
Almost 500,000 men and women answered questions about their physical activity, body weight and height. Over the next eight years, 480 of the participants developed glioma brain tumours.
Physical activity during adolescence was associated with reduced cancer risk.
Volunteers who were obese as adolescent teenagers were three to four times more prone to glioma than people whose weight was normal at this time of life. However, the researchers pointed out that the numbers of these individuals were small.
Dr Steven Moore, from the US National Cancer Institute, said: "Our findings suggest that biological factors related to energy expenditure and growth during childhood may play a role in glioma aetiology (causation).
"This clue could help researchers better understand important features of gloom biology and the potentially modifiable lifestyle factors that could be important in preventing the disease..
"These results were surprising, but to our knowledge no-one has looked at glioma risk as related to energy balance in childhood and adolescence before."
The findings were reported online today in the journal Cancer Research.
Professor Christine Ambrosone, a cancer prevention specialist and one of the journal's editors, said: "These results highlight the potential importance of habits during childhood and adolescence for risk of brain cancer later in life. Additional research is needed to understand the biologic mechanisms that underlie these relationships."Reuse content