Laparoscopic surgery

Colon Cancer

  • 9-29-2011
  • Categorized in: Cancer

A.D.A.M. Medical Encyclopedia.

Colorectal cancer; Cancer - colon; Rectal cancer; Cancer - rectum; Adenocarcinoma - colon; Colon - adenocarcinoma
Last reviewed: December 28, 2010.

 

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Colon, or colorectal, cancer is cancer that starts in the large intestine (colon) or the rectum (end of the colon).

Other types of cancer can affect the colon, such as lymphoma, carcinoid tumors, melanoma, and sarcomas. These are rare. In this article, use of the term "colon cancer" refers to colon carcinoma only.

Causes, incidence, and risk factors

According to the American Cancer Society, colorectal cancer is one of the leading causes of cancer-related deaths in the United States. However, early diagnosis often leads to a complete cure.

Almost all colon cancer starts 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 higher risk for colon cancer if you:

  • Are older than 60
  • Are African American of eastern European descent
  • Eat a diet high in red or processed meats
  • Have cancer elsewhere in the body
  • 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 genetic syndromes 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 associated with a high-fat, low-fiber diet and red meat. However, some studies 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, however, may indicate colon cancer:

Signs and tests

With proper screening, colon cancer can be detected before symptoms develop, when it is most curable.

Your doctor will perform a physical exam and press on your belly area. The physical exam rarely shows any problems, although the doctor may feel a lump (mass) in the abdomen. A rectal exam may reveal a mass in patients with rectal cancer, but not colon cancer.

A fecal occult blood test (FOBT) may detect small amounts of blood in the stool, which could suggest colon cancer. However, this test is often negative in patients with colon cancer. For this reason, a FOBT must be done along with colonoscopy or sigmoidoscopy. It is also important to note that a positive FOBT doesn't necessarily mean you have cancer.

Imaging tests to screen for and potentially diagnose colorectal cancer include:

Note: Only colonoscopy can see the entire colon, and this is the best screening test for colon cancer.

Blood tests that may be done include:

If your doctor learns that you do have colorectal cancer, more tests will be done to see if the cancer has spread. This is called staging. CT or MRI scans of the abdomen, pelvic area, chest, or brain may be used to stage the cancer. Sometimes, PET scans are also used.

Stages of colon cancer are:

  • Stage 0: Very early cancer on the innermost layer of the intestine
  • Stage I: Cancer is in the inner layers of the colon
  • Stage II: Cancer has spread through the muscle wall of the colon
  • Stage III: Cancer has spread to the lymph nodes
  • Stage IV: Cancer has spread to other organs

Blood tests to detect tumor markers, including carcinoembryonic antigen (CEA) and CA 19-9, may help your physician follow you during and after treatment.

Treatment

Treatment depends partly on the stage of the cancer. In general, treatments may include:

 

A.D.A.M., Disclaimer


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