Exercise is already known to reduce the risk of breast, colon and endometrial cancer by between 10% and 40%.
A new analysis of data from studies looking at about 1.4 million adults between the ages of 19 and 98 has found that exercise reduces the risk of an additional 10 cancers, including esophageal, stomach bladder and kidney.
Additionally, a study found that for many cancers, exercise reduces the risk even in overweight patients. This is especially interesting because the mechanism by which exercise is thought o protect form cancer is weight reduction.
Some researchers assert that exercise may help to repair DNA that is damaged by cancer-promoting substances and others say that exercise may also alter hormone levels and reduce inflammation.
The study showed that the risk of esophageal cancer for those engaging in the most exercise was 42% lower than for those engaging in the least. For seven of the cancers, the risk reduction was one-fifth or more.
The data was based on four hours of activity a week, which is the standard recommendation to prevent heart disease.
A second study, which took data from 136,000 Americans, found that anyone who quits smoking; does two and a half hours of moderate exercise a week has no more than one drink a day if a woman or two if a man; and keeps to a BMI between 18.5 and 27.5 is likely to reduce their bowel cancer by 30% and breast cancer by 12%.
Although these studies only report an observed association and can’t prove that exercise reduces the risk of cancer, they show that there is a strong link. Any type of exercise is beneficial, even taking the stairs instead of the elevator.