From a BBC story today:

Over 40% of breast and bowel cancer cases in rich countries are preventable through diet, physical activity and weight control alone, experts say.

Simple measures like cycling to work and swapping fatty foods for fruit can make all the difference for these and many other cancers, they say.

Hm. Just cycling to work, huh? While the numbers seem a bit inflated to me, this is still something to feel smug about I guess. This should give some more energy to the active transportation movement.