Increasing the amount of leisure-time physical activity has been shown to lower the risk of 13 types of cancer, according to the National Institutes of Health.
http://www.newsminer.com/features/health/physical-activity-linked-to-reduced-rates-of-cancer/article_a447f230-20b6-11e6-9269-5be5ebe9fe35.html
Physical activity linked to reduced rates of cancer