The colon is part of the body's digestive system. The digestive system is made up of the esophagus, stomach, and the small and large intestines. The last 6 feet of intestine is called the large bowel or colon.
Genes are markers in cells associated with hereditary traits.
Abnormal genes have been found in patients with some forms of colon and rectal cancer. Tests are being developed to determine who carries these genes long before cancer appears. A doctor may order these tests to look for cancer if there is a change in bowel habits or if there is any bleeding from the rectum. A doctor will usually begin by giving the patient a rectal examination. In a rectal examination the doctor, wearing thin gloves, puts a greased finger into the rectum and gently feels for lumps.