Older adults who are heavy, especially around the middle, seem to have a higher risk of developing colon cancer than their thinner peers - and exercise may lower the incidence of the disease, especially for women, a European study said. More than 120,000 adults in the Netherlands aged 55 to 69 were followed for 16 years by the study, published in the American Journal of Epidemiology. During that time, about 2% developed colorectal cancer, tumours of colon or rectum, though most were diagnosed with colon cancer.