Nearly 150,000 people were diagnosed with colorectal cancer in the United States in 2008, the most recent year we have data for, with roughly 50,000 deaths attributed to this disease.
It is the second leading cause of cancer death among cancers that affect both men and women, although it is one thought to be largely preventable, with rates 10-fold higher reported in Western countries.
One study conducted among nearly 50,000 men found that over 70% of colorectal cancer incidence could be prevented by diet, physical activity, and specific health behaviors, such as refraining from smoking.
Nearly all colorectal cancers are adenocarcinomas, with the great majority arising from an adenomatous polyp. Recently, 6 lifestyle factors were found to cumulatively increase the risk for adenomas. This provides strong evidence that lifestyle modification is important for the prevention of colorectal polyps, especially advanced and multiple adenomas, which are established precursors of colorectal cancer.:
Colorectal cancer occurs more commonly in those over age 50, men, and individuals of African-American descent, and those with a family history of colorectal cancer or a personal history of polyps, inflammatory bowel disease, or low socioeconomic status.
Smoking increases the risk for colorectal cancer for as long as 25 years after quitting, although having a normal body mass index (BMI) and having high fruit consumption mitigate this risk to a small degree.
Other dietary factors associated with risk include consumption of animal foods, particularly red and processed meat and low fiber and calcium intake.
Alcohol and an elevated BMI are also risk factors, while physical activity has a dose-dependent benefit for reducing risk.
A number of screening tests for colorectal cancer are available, and require a physician’s guidance to determine the most appropriate. Colonoscopy, for example, is the most likely to find polyps or cancer, but also to have complications such as bowel tears or infection.
Several tumor markers may be used to monitor progress or guide treatment decisions, including carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA19-9), and tissue polypeptide antigen (TPA).
Low Vitamin D levels have been associated with the risk of developing colorectal cancer, as well as both overall and colorectal cancer specific mortality.
Multiple nutritional supplements have been associated with reduced cancer incidence and/or cancer progression. The list below contains those with the greatest evidence-base and benefit, though it is not necessary that they all be included.
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