Colorectal cancer, which is the third most common cancer in men and the second most common in women, represents almost 10% of the annual global cancer incidence. Incidence rates of colorectal cancer show a strong positive gradient with an increasing level of economic development. Even so, the net 5-year rate of survival decreases with lower levels of income, with rates reaching 60% in high-income countries but falling to 30% or less in low-income countries.
Established risk factors for colorectal cancer include consumption of processed meats, consumption of alcoholic beverages, tobacco smoking, and excess body fat, whereas consumption of dietary fiber and dairy products and increased levels of physical activity decrease the risk. In addition, certain subgroups of the population are at increased risk owing to genetic predisposition (e.g., the Lynch syndrome), a family or personal history of colorectal neoplasia, or medical conditions (e.g., inflammatory bowel disease) that have been associated with colorectal cancer.