Epidemiology and risk factors for colorectal cancer

Striking geographic differences in the incidence of colorectal cancer and changes in disease risk among immigrants from low to high incidence areas suggest the importance of the environment as a factor in colorectal cancer risk. Among the best studied factors are dietary fiber, vegetables, fruits, vitamins, dietary anticarcinogens, vitamins, and trace metals. Lifestyle factors such as obesity, inactivity, and cigarette smoking may also be important. There is exciting new information on chemopreventive agents such as aspirin and nonsteroidal anti-inflammatory drugs that may someday be proven effective in preventing colorectal cancer.