Exercise and Cancer

http://www.marksdailyapple.com/the-link-between-cancer-and-exercise/
"First of all, it has been shown that exercise can significantly reduce a person's risk of developing cancer. For women especially, regular exercise is an important cancer deterrent. Coupled with plenty of rest, moderate doses of physical activity have "consistently been associated with reduced risk of cancer incidence at several sites, including breast and colon cancers." Scientists suspect the preventive powers of exercise can be linked to its effect on hormones, body weight, and immune system strength, but they're not sure.
And, as the Swedish medical school Karolinska Institutet so bluntly put it, exercise "cuts cancer death in men," too. The Swedish researchers examined some forty thousand men of varying ages for seven years. Of that group, around 3700 developed cancer; 1,153 died from it. For those cancer patients who also walked or cycled for at least thirty minutes a day, the survival rate increased 33% against those who didn't exercise at all. An extensive (60 to 90 minutes a day) exercise program was even shown to reduce the incidence of cancer by 16%.
New research also shows that it's never too early to start reaping the benefits of regular exercise. Beginning as early as age twelve, girls and young women who exercise regularly enjoy a substantially lower risk of getting breast cancer before menopause. A study of almost 65,000 women revealed that active women had a 23% reduced risk. Furthermore, early exercise - between the ages of 12 and 22 - had the most effect on risk later in life."