Habitual physical activity reduces cancer risk by what percent in breast and colon?

• A. 5-10%
• B. 60-70%
• C. 20-40%
• D. 0%

Answer: (C)

Regular physical activity lowers the risk of several cancers, including breast and colon, through multiple mechanisms such as helping maintain a healthy body weight, improving insulin sensitivity, reducing inflammation, and favorably influencing hormone levels.

Across large studies, the reductions seen with habitual activity fall roughly in the 20-40% range when comparing active to inactive people. The exact amount varies with how much and how intensely you exercise, as well as individual factors like age, menopausal status, and body composition. Colon cancer often shows somewhat larger reductions with higher activity, while breast cancer risk reduction can vary more by population factors, but the overall message is a meaningful, nontrivial decrease.

So, the range that best reflects the typical combined effect for breast and colon cancers is about 20-40% reduction.