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Colon cancer


Alternative Names:

Colorectal cancer; Cancer - colon; Rectal cancer; Cancer - rectum; Adenocarcinoma - colon; Colon - adenocarcinoma

Causes, incidence, and risk factors:

Colorectal cancer is one of the leading causes of cancer-related deaths in the United States. Early diagnosis, though, can often lead to a complete cure.

Almost all colon cancers start in glands in the lining of the colon and rectum. When doctors talk about colorectal cancer, this is usually what they are talking about.

There is no single cause of colon cancer. Nearly all colon cancers begin as noncancerous (benign) polyps, which slowly develop into cancer.

You have a high risk of colon cancer if you:

  • Are older than 60
  • Are African American of eastern European descent
  • Eat a a lot of red or processed meats
  • Have colorectal polyps
  • Have inflammatory bowel disease (Crohn's disease or ulcerative colitis)
  • Have a family history of colon cancer
  • Have a personal history of breast cancer

Certain inherited diseases also increase the risk of developing colon cancer. Two of the most common are:

  • Familial adenomatous polyposis (FAP)
  • Hereditary nonpolyposis colorectal cancer (HNPCC), also known as Lynch syndrome

What you eat may play a role in your risk of colon cancer. Colon cancer may be linked to a high-fat, low-fiber diet and to a high intake of red meat. Some studies, though, have found that the risk does not drop if you switch to a high-fiber diet, so this link is not yet clear.

Smoking cigarettes and drinking alcohol are other risk factors for colorectal cancer.

Symptoms:

Many cases of colon cancer have no symptoms. The following symptoms may indicate colon cancer:

Treatment:

Treatment depends on many things, including stage of the cancer. Treatments may include:

Surgery

Stage 0 colon cancer may be treated by removing the cancer cells. This is done using colonoscopy. For stages I, II, and III cancer, more extensive surgery is needed to remove the part of the colon that is cancerous. This surgery is called colon resection.

Chemotherapy

Almost all patients with stage III colon cancer should receive chemotherapy after surgery for 6 - 8 months. This is called adjuvant chemotherapy. The drug 5-fluorouracil can increase the chance of a cure in certain patients.

Chemotherapy is also used to improve symptoms and prolong survival in patients with stage IV colon cancer.

  • Irinotecan, oxaliplatin, capecitabine, and 5-fluorouracil are the three most commonly used drugs.
  • Monoclonal antibodies, including cetuximab (Erbitux), panitumumab (Vectibix), bevacizumab (Avastin), and other drugs have been used alone or in combination with chemotherapy.

You may receive just one type, or a combination of these drugs. There is some debate as to whether patients with stage II colon cancer should receive chemotherapy after surgery. You should discuss this with your oncologist.

Radiation

Radiation therapy is sometimes used in patients with colon cancer. It is usually used in combination with chemotherapy for patients with stage III rectal cancer.

For patients with stage IV disease that has spread to the liver, treatments directed at the liver can be used. This may include:

  • Burning the cancer (ablation)
  • Delivering chemotherapy or radiation directly into the liver
  • Freezing the cancer (cryotherapy)
  • Surgery
Support Groups:

You can ease the stress of illness by joining a colon cancer support group. Sharing with others who have common experiences and problems can help you not feel alone. 

Expectations (prognosis):

In many cases, colon cancer is treatable when it is caught early.

How well you do depends on many things, especially the stage of the cancer. When treated at an early stage, many patientssurvive at least 5 years after diagnosis. This is called the 5-year survival rate.

If the colon cancer does not come back (recur) within 5 years, it is considered cured. Stage I, II, and III cancers are considered possibly curable. In most cases, stage IV cancer is not considered curable, although there are exceptions.

Complications:
  • Blockage of the colon, causing bowel obstruction
  • Cancer returning in the colon
  • Cancer spreading to other organs or tissues (metastasis)
  • Development of a second primary colorectal cancer
Calling your health care provider:

Call your health care provider if you have:

  • Black, tar-like stools
  • Blood during a bowel movement
  • Change in bowel habits
  • Unexplained weight loss
Prevention:

The death rate for colon cancer has dropped in the last 15 years. This may be due to increased awareness and screening by colonoscopy.

Colon cancer can almost always be caught by colonoscopy in its earliest and most curable stages. Almost all men and women age 50 and older should have a colon cancer screening. Patients at higher risk may need earlier screening.

Colon cancer screening can often find polyps before they become cancerous. Removing these polyps may prevent colon cancer.

Changing your diet and lifestyle is important. Medical research suggests that low-fat and high-fiber diets may reduce your risk of colon cancer.

Some studies have reported that NSAIDs (aspirin, ibuprofen, naproxen, celecoxib) may help reduce the risk of colorectal cancer. But these medicines can increase your risk of bleeding and heart problems. Your health care provider can tell you more about the risks and benefits of the medicines and other ways that help prevent colorectal cancer.

References:

Cunningham D, Atkin W, Lenz HJ, Lynch HT, Minsky B, Nordlinger B, et al. Colorectal cancer. Lancet. 2010;375:1030-1047.

National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines): Colon cancer. Version 2.2013. Available at http://www.nccn.org/professionals/physician_gls/pdf/colon.pdf. Accessed November 16, 2012.

Smith RA, Cokkinides V, Brawley OW. Cancer screening in the United States, 2012: a review of current American Cancer Society guidelines and current issues in cancer screening. CA Cancer J Clin. 2012;62:129-142.


Review Date: 11/17/2012
Reviewed By: Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, Stephanie Slon, and Nissi Wang.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2002 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

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