The reasons for decreasing trends in incidence and mortality are not well understood. The decrease in mortality may also be related to decreasing incidence and improved survival. Progress in reducing death rates from colorectal cancer has been greater among whites than African Americans. Rates for African-American women have remained stable over time. Over half of the poorer survival in African Americans compared to whites can be attributed to diagnosis of colorectal cancer at a later stage.
Older age is the single most important risk factor for the development of colorectal cancer.
A personal history of colon cancer, intestinal adenomatous polyps, or inflammatory bowel disease also increase a person s likelihood of developing colorectal cancer. Participation in regular physical activity may reduce a person s risk for developing colon cancer. Obesity has been shown to increase the risk for colon cancer in men. Current use of hormone replacement therapy may decrease the risk for developing colorectal cancer in postmenopausal women. Men and women who use nonsteroidal antiinflammatory drugs may have a decreased risk for developing colon cancer and other cancers of the digestive tract.