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Colon Cancer

Cancer that forms in the tissues of the colon (the longest part of the large intestine). NIH - National Cancer Institute

About Colon Cancer

Colon cancer is a disease in which malignant (cancer) cells form in the tissues of the colon.

The colon is part of the body's digestive system. The digestive system removes and processes nutrients (vitamins, minerals, carbohydrates, fats, proteins, and water) from foods and helps pass waste material out of the body. The digestive system is made up of the esophagus, stomach, and the small and large intestines. The first 6 feet of the large intestine are called the large bowel or colon. The last 6 inches are the rectum and the anal canal. The anal canal ends at the anus (the opening of the large intestine to the outside of the body).

Gastrointestinal stromal tumors can occur in the colon. See the PDQ summary on Gastrointestinal Stromal Tumors Treatment for more information... Read more about Colon Cancer

What works? Research summarized

Evidence reviews

Venous Thromboembolism: Reducing the Risk of Venous Thromboembolism (Deep Vein Thrombosis and Pulmonary Embolism) in Patients Admitted to Hospital

Venous thromboembolism (VTE) is a term used to include the formation of a blood clot (a thrombus) in a vein which may dislodge from its site of origin to travel in the blood, a phenomenon called embolism. A thrombus most commonly occurs in the deep veins of the legs; this is called deep vein thrombosis. A dislodged thrombus that travels to the lungs is known as a pulmonary embolism.

CT colonography ("virtual colonoscopy") for colon cancer screening

Bibliographic details: Mark D.  CT colonography ("virtual colonoscopy") for colon cancer screening. Chicago, IL, USA: Blue Cross and Blue Shield Association, Technology Evaluation Center. TEC Assessment Program; 19(6). 2004

Diagnostic performance of chromoendoscopy and narrow band imaging for colonic neoplasms: a meta-analysis

The review concluded that chromoendoscopy and narrow band imaging had similar diagnostic performance for assessing colonic neoplasms, but both gave unacceptably high false positive rates. These conclusions reflect the data presented, but should be interpreted cautiously due to limitations in study selection, quality assessment and analysis.

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Summaries for consumers

Colon Cancer Treatment (PDQ®): Patient Version

Expert-reviewed information summary about the treatment of colon cancer.

Adjuvant therapy for completely resected stage II colon cancer

Colon cancer is the second most common cause of cancer deaths in the Western world. A large proportion of colon cancer patients can be cured by surgical resection alone. For those patients with lymph node positive (stage III) disease, the recurrence rate can exceed 50% and adjuvant chemotherapy has been shown to significantly reduce the risk of recurrence. In patients without lymph node involvement (stage I and II), the prognosis is quite good with surgery alone, with survival rates of 75% to 95% at 5 years. However, some patients with high risk stage II disease have a relapse rate approaching that of stage III colon cancer patients. Due to the effectiveness of systemic chemotherapy in stage III disease, a similar approach has been considered for patients with stage II disease. We performed a systematic review looking at all randomized clinical trials evaluating stage II colon cancer patients and adjuvant therapy versus surgery alone. Our review found that adjuvant therapy ‐either systemic or regional chemotherapy or immunotherapy‐ can improve the outcomes of stage II patients. In counselling individual patients, the advice given should be conditioned by the patient's age and comorbidities. In addition, the high risk features of the tumour should also be considered when contemplating the benefits of systemic therapy in patients with stage II colon cancer. Further investigation is needed to elucidate which patient and tumour factors can be used to select stage II colon cancer patients for adjuvant therapy. There also exists a need to continue to search for other adjuvant therapies which might be more effective, shorter in duration and less toxic than those available today.

Strategies for detecting colon cancer and/or dysplasia in patients with inflammatory bowel disease

Patients with long‐standing ulcerative colitis and colonic Crohn's disease have an increased risk of colorectal cancer compared with the general population. This review shows that there is no conclusive evidence that surveillance colonoscopy prolongs survival in these patients. However, since the principal studies were completed it has become clear that numerous biopsies are needed to accurately identify pre‐cancerous lesions (dysplasia) and that the benefit of surveillance could have been greater if multiple biopsies had been performed. It has also since been demonstrated that targeted biopsy of dysplastic areas is enhanced by dye spraying at colonoscopy. There is evidence from case control studies that cancers tend to be detected at an earlier stage in patients who are undergoing surveillance and that these patients have a better chance for recovery. This evidence should be treated with caution since lead‐time bias (the period between early detection of disease and the time of its usual clinical presentation) may contribute substantially to this apparent benefit. It is unlikely that there will be a randomised trial of surveillance colonoscopy in patients with colitis. Lower quality evidence, however, supports the continued use of some form of surveillance for these patients. The nature of this surveillance is gradually evolving, with two important developments since the last version of this review in 2004. Firstly, it has become apparent that most pre‐malignant (dysplastic) lesions can be visualised with careful endoscopy. Secondly, patients who lack histological inflammation on colonoscopy are at low risk for cancer development.

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Terms to know

The longest part of the large intestine, which is a tube-like organ connected to the small intestine at one end and the anus at the other. The colon removes water and some nutrients and electrolytes from partially digested food. The remaining material, solid waste called stool, moves through the colon to the rectum and leaves the body through the anus.
Gastrointestinal Stromal Tumor (GIST)
A type of tumor that usually begins in cells in the wall of the gastrointestinal tract.
Large Intestine
The part of the intestine that includes the appendix, cecum, colon, and rectum. The large intestine absorbs water from stool and changes it from a liquid to a solid form. The large intestine is 5 feet long.
The last several inches of the large intestine closest to the anus.

More about Colon Cancer

Photo of an adult

Also called: Malignant tumour of the colon, Malignant tumor of the colon, Cancer of the colon

Other terms to know: See all 4
Colon, Gastrointestinal Stromal Tumor (GIST), Large Intestine

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Information for Health Professionals

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