Habitually active people have a 20-40% reduction in cancer risk in which sites?

• A. Lung & pancreas
• B. Brain & prostate
• C. Breast & colon
• D. Skin & thyroid

Answer: (C)

Regular physical activity lowers cancer risk, with the strongest and most consistent evidence for breast and colon cancers, showing about a 20-40% reduction for people who stay habitually active. This protection comes from several mechanisms: reduced body fat lowers estrogen exposure (important for breast cancer risk), improved insulin sensitivity and lower circulating growth factors, and decreased chronic inflammation and enhanced immune function. For colon cancer, exercise also speeds up gut transit, decreasing the time the colonic lining is exposed to potential carcinogens and supporting healthier bowel function. Other sites like the brain, prostate, skin, thyroid, lung, or pancreas have weaker or inconsistent evidence for a protective effect, so the clear, well-supported reductions are seen in breast and colon cancers.