Exercise Tied to Lower Risk for 13 Types of Cancer (and higher risk for 2)

... The researchers found a reduced risk of breast, lung and colon cancers, which had been reported in earlier research. But they also found a lower risk of tumors in the liver, esophagus, kidney, stomach, endometrium, blood, bone marrow, head and neck, rectum and bladder.

And the reductions in risk for any of these 13 cancers rose steeply as people exercised more. When the researchers compared the top 10 percent of exercisers, meaning those who spent the most time each week engaging in moderate or vigorous workouts, to the 10 percent who were the least active, the exercisers were as much as 20 percent less likely to develop most of the cancers in the study.

On the other hand, they found an increased risk of two types of malignancies — melanoma and slow-growing prostate tumors — among people who exercised the most.

Encouragingly, the associations between exercise and reduced cancer risks held true even when the researchers factored in body mass. People who were overweight or obese but exercised had a much lower risk of developing most cancers than overweight people who did not move much.

Bear in mind, though, that this was an observational study, so it cannot directly prove that exercise reduces cancer risks, only that there is an association between more exercise and less disease. It also relied on participants’ memories of exercise, which can be unreliable.