Although researchers publishing online in the Journal of Cancer Research admit that "only" half of the cancers are affected by lifestyle conditions of inactivity and obesity, I'd say that is a huge "half", at 54%. Remember that although colonoscopy may identify colon cancer at an early stage and therefore be helpful, the reins of control are in your hands for half of those getting colon cancer. Avoid obesity - see the Weight Loss Plan in the Real Food section of this website - and maintain some level of physical activity throughout life.