http://www.cnn.com/2013/05/16/health...html?hpt=hp_t3

Exercise may keep cancer away

Getting into shape may help you ward off cancer -- or boost your survival chances if you are diagnosed, according to a new study.

Researchers from the University of Vermont studied more than 17,000 men for close to 20 years. They found those who exercised the most were 68% less likely to develop lung cancer and 38% less likely to develop colorectal cancers than the least active men.

Among those men who did develop either of those two cancers or prostate cancer, exercise helped reduce the risk of death by 14% for each incremental increase in fitness level.
This is pretty impressive stuff.

So..not only does regular exercise seem to ward off some of the most common and deadly cancers, but the effect "stacks" as they say.

Some interesting live ASCO discussion on the topic...

http://meetinglibrary.asco.org/content/34803