Whether or not you drop pounds, you can at least get more active. Though the evidence that this will lower your cancer risk is inconclusive so far, there are encouraging signs.
For instance, in a study published in 2006, researchers considered the effects of a 12-month program of aerobic exercise. The participants were 100 women and 102 men, ages 40 to 75 years, all healthy and having undergone a colonoscopy within the last three years. Before the study, they had led lives of sedentary ease, and now half were asked to continue their normal exercise habits, such as they were.
But the other half worked up to working out six days a week, for 60 minutes a day, mostly on treadmills and stationary bikes. Men who successfully completed the program showed a significant lowering of two biomarkers associated with colon cancer risk — increased proliferation of cells in the lining of the colon and an extension of the zone where such proliferation takes place. For women, there was no change.
The study couldn't show that people actually reduced their cancer risk — it only measured signs that have been associated with cancer risk. But these signs pointed in the right direction.