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Colon cancer

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

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. These include lymphoma, carcinoid tumors, melanoma, and sarcomas. These are rare. In this article, colon cancer refers to colon carcinoma only.

Images

Barium enema
Colonoscopy
Digestive system
Rectal cancer, X-ray
Sigmoid colon cancer, X-ray
Spleen metastasis - CT scan
Structure of the colon
Stages of cancer
Colon culture
Large intestine (colon)

Presantation

Colon cancer - Series
Colostomy - Series
Large bowel resection - Series

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Causes

In the United States, colorectal cancer is one of the leading causes of deaths due to cancer. Early diagnosis can often lead to a complete cure.

Almost all colon cancers start 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:

Some inherited diseases also increase the risk of developing colon cancer. One of the most common is called familial adenomatous polyposis (FAP).

What you eat may play a role in getting colon cancer. Colon cancer may be linked to a high-fat, low-fiber diet and to a high intake of red meat. 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. If there are symptoms, the following may indicate colon cancer:

Exams and Tests

Through screening tests, colon cancer can be detected before symptoms develop. This is when the cancer 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 people with rectal cancer, but not colon cancer.

A fecal occult blood test (FOBT) may detect small amounts of blood in the stool. This may suggest colon cancer. A sigmoidoscopy, or more likely, a colonoscopy, will be done to evaluate the cause of blood in your stool.

Only a full colonoscopy can see the entire colon. This is the best screening test for colon cancer.

Blood tests may be done for those diagnosed with colorectal cancer, including:

If you are diagnosed with 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:

Blood tests to detect tumor markers, such as carcinoembryonic antigen (CEA) may help the doctor follow you during and after treatment.

Treatment

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

SURGERY

Stage 0 colon cancer may be treated by removing the tumor. This is often 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(colectomy).

CHEMOTHERAPY

Almost all people with stage III colon cancer receive chemotherapy after surgery for 6 to 8 months. This is called adjuvant chemotherapy. Even though the tumor was removed, chemotherapy is given to treat any cancer cells that may be left.

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

You may receive just 1 type of medicine or a combination of medicines.

RADIATION

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

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

TARGETED THERAPY

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.

Outlook (Prognosis)

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

How well you do depends on many things, especially the stage of the cancer. When treated at an early stage, many people survive 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. Stages I, II, and III cancers are considered possibly curable. In most cases, stage IV cancer is not considered curable, although there are exceptions.

Possible Complications

Complications may include:

When to Contact a Medical Professional

Call your health care provider if you have:

Prevention

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. People 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 for colon cancer.

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

Related Information

Cancer
Hodgkin lymphoma
Melanoma
Colorectal polyps
Ulcerative colitis
Metastasis
Virtual colonoscopy
Ileostomy
Total proctocolectomy and ileal - anal pouch
Total proctocolectomy with ileostomy
Chemotherapy - what to ask your doctor
Radiation therapy - questions to ask your doctor
Changing your ostomy pouch
Ileostomy - what to ask your doctor
Abdominal radiation - discharge
Pelvic (between the hips) radiation - discharge
Bland diet
Ileostomy and your child
Ileostomy and your diet
Ileostomy - caring for your stoma
Ileostomy - changing your pouch
Types of ileostomy
Ileostomy - discharge
Living with your ileostomy
Large bowel resection - discharge
Small bowel resection - discharge
Total colectomy or proctocolectomy - discharge

References

Itzkowitz SH, Potack J. Colonic polyps and polyposis syndromes. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 10th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 126.

National Cancer Institute: PDQ colon cancer treatment. Bethesda, MD: National Cancer Institute. Date last modified January 7, 2016. Available at: www.cancer.gov/types/colorectal/hp/colon-treatment-pdq. Accessed January 18, 2016.

National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines): Colon cancer. Version 2.2016. Available at: www.nccn.org/professionals/physician_gls/pdf/colon.pdf. Accessed January 18, 2016.

National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines): Rectal cancer. Version 1.2016. Available at: www.nccn.org/professionals/physician_gls/pdf/rectal.pdf. Accessed January 18, 2016.

Van Schaeybroeck S, Lawler M, Johnston B, et al. Colorectal cancer. In: Niederhuber JE, Armitage JO, Doroshow JH, Kastan MB, Tepper JE, eds. Abeloff's Clinical Oncology. 5th ed. Philadelphia, PA: Elsevier; 2014:chap 77.

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Review Date: 12/4/2015  

Reviewed By: Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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