Exercising more could reduce a man's risk of prostate cancer by over 50%, say scientists from the University of Bristol.
The scientists studied 140,000 men, of which 80,000 had prostate cancer. They found the variation in their DNA sequence that makes them more likely to exercise had a positive affect on reducing their risk of developing prostate cancer by 51%. The findings relate to overall physical activity, not just intense exercise.
"This study is the largest-ever of its kind, which uses a relatively new method that complements current observational research to discover what causes prostate cancer," said Dr Sarah Lewis, senior lecturer in genetic epidemiology at Bristol Medical School: Population Health Sciences, and lead author of the research.
"We think that the genetic variants are only influencing prostate cancer via an effect on activity, so without the activity there's no effect on prostate cancer. The genes were just used to divide the population into groups, which on average have high or low activity. Therefore there would be no effect of the genes without physical activity.
"It suggests that there could be a larger effect of physical activity on prostate cancer than previously thought, so will hopefully encourage men to be more active."
Prostate cancer is the most common cancer among UK men, but little is still understood about its causes. Previous research has shown exercise can reduce the risk of bowel, breast and uterus cancer, but before now there has been little evidence of ways to reduce prostate cancer risk other than maintaining a healthy weight.
Dr Anna Diaz Font, head of research funding at WCRF, said: "Up until now, there has only been limited evidence of an effect of physical activity on prostate cancer. This new study looked at the effect of 22 risk factors on prostate cancer, but the results for physical activity were the most striking. This will pave the way for even more research, where similar methods could be applied to other lifestyle factors, to help identify ways men can reduce their risk of prostate cancer."