In the gastrointestinal system, the colon is the "segment of large intestine between the cecum and the rectum. It includes the ascending colon, the transverse colon, the descending colon, and the sigmoid colon."
There are many disorders of the colon, and colorectal cancer is a serious one. In the U.S., there were an estimated 108,070 new case of colon and 40,740 rectal cancer in 2008, with 49,760 deaths for the combined colorectal category.
Risk factors for colon disease
Risk factors for colon cancer probably include some genetic predisposition. A low-fat, high fiber may have a role, but the data are inconclusive. There has been evidence that aspirin and other non-steroidal anti-inflammatory drugs may have a role in prevention. Some of the selective cyclooxygenase 2 inhibitors may have even stronger preventive effect, but these also carry significant cardiovascular risk and probably cannot be justified for preventive use. 
Disease and treatment
Irritable bowel syndrome
Inflammatory bowel disease
A variety of inflammatory syndromes, such as Crohn's disease, affect the gastrointestinal system, including the colon.
Many infectious diseases can affect the colon. A current area of concern involves the increasing incidence of disease from Clostridium difficile, which tends to be an overgrowth due to disturbance in the colon microflora rather than a completely foreign infection. C. difficile can cause presentations from mild diarrhea to life-threatening pseudomembranous enterocolitis. While it has most commonly been regarded as nosocomial, often as a result of oral antibiotics, community-acquired cases are seen. Hospital-acquired infection is being regarded as a significant issue in healthcare economics; some third-party payors will not reimburse for its treatment, considering it preventable, a controversial claim.
Early detection of abnormalities
Early detection and treatment improves the chance of successful treatment; the best screening and diagnostic methods are still the subject of investigation. They range from noninvasive testing of feces for blood, and various direct viewing techniques, using a flexible optical sigmoidoscope or more intrusive colonoscope. 
The role of promising new gastrointestinal imaging techniques, such as a single-use miniaturized camera that is swallowed, transmits to viewers outside the body, and such as computerized tomography, with and without contrast agents, is still not firmly established. The noninvasive methods clearly are more comfortable and generally have lower risk, but they cannot provide biopsy material, or early-interventional surgical removal of suspicious tissue.
- Anonymous (2015), Colon (anatomy) (English). Medical Subject Headings. U.S. National Library of Medicine.
- National Cancer Instute, National Institutes of Health, Colon and Rectal Cancer
- National Cancer Instute, National Institutes of Health (12/19/2008), Genetics of Colorectal Cancer (PDQ®), Health Professional Version
- Craig A Gronczewski, Jonathan P Katz (Aug 10, 2006), "Clostridium Difficile Colitis", eMedicine
- National Cancer Instute, National Institutes of Health, Colorectal Cancer Screening (PDQ®)