Colon cancer is cancer that starts in colon (or large intestine). The colon absorbs water and nutrients from foods. Then it passes solid waste to the rectum for storage. It stays there until it’s eliminated from the body.
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Cancer is when cells in the body split without control or order. These cells go on to form a growth or tumor. The term cancer refers to harmful growths. These growths attack nearby tissues. They also spread to other parts of the body. It’s not clear exactly what causes these problems. It’s likely a mix of genes and the environment.
Your chances are higher for:
- Age 50 years and older
- Being male
- Inherited diseases such as familial adenomatous polyposis
- Prior colon or rectal cancer, or polyps
- Having certain genes
- Colon or rectal cancer in your family—mainly with a parent, sibling, or child
- Ulcerative colitis or Crohn disease
- Lifestyle factors such as:
People of the Black race have the highest chance of getting and dying from colon and rectal cancers.
You may not notice any symptoms at first. When present, colon cancer may cause:
- Bleeding without other problems
- A change in bowel habits
- Blood in the stool that is either bright red, or black and tarry
- Pain or pressure
- Feeling of a mass
- Belly pain
- Weight loss
- Feeling tired
- Breathing problems and pale skin—signs of anemia
The doctor will ask about your symptoms and health history. Your answers and a physical exam may point to colon cancer. You may also have:
- A digital rectal exam—the doctor will feel for lumps with a lubricated, gloved finger in the rectum
- Blood tests
- Endoscopy such as:
- Imaging tests such as:
- Biopsy —a sample of intestinal tissue is tested in a lab (done during endoscopy)
The exam and your test results will help find out the stage of cancer you have. Staging guides your treatment. Colon cancer is staged from 0-4. Stage 0 is a very localized cancer. Stage 4 is a spread to other parts of the body.
How colon cancer is treated depends on:
- How early it’s found
- Where the tumor is
- The stage of cancer
Colon cancer is treated with more than one method. Sometimes they’re combined. This can be done with:
Surgery is the main way to treat colon cancer. This is done with:
- Polypectomy and local excision—Cancer is removed during a sigmoidoscopy or colonoscopy.
- Partial colectomy —A border of healthy tissue along with the cancer is removed. The healthy ends of the colon are reconnected.
- Laparoscopic-assisted colectomy —A border of healthy tissue along with the cancer is removed. This is done through small cuts in the belly. Tubes are placed in the cuts. Tools and lights are used through the tubes.
- Total colectomy—The colon is taken out. This results in the need for a colostomy. A path for solid waste to pass from the body is made through the belly wall. A special bag is needed to collect the waste.
Radiation therapy is the use of radiation to kill cancer cells and shrink tumors. It may be given at the same time as chemotherapy. The types are:
- External—radiation is aimed at the tumor from a source outside the body
- Internal—radioactive materials are placed into the body near the cancer cells
Chemotherapy is the use of drugs to kill cancer cells. It may given by mouth, shots, or IV. The drugs enter the bloodstream and travel throughout the body.
These medicines block tumors from growing and spreading. It may be used with other methods. In many cases, these medicines aren’t used until cancer is in later stages.
Some medicines are part of treatment. Others may help control side effects. These may include:
- Medicines to make more red or white blood cells
- Anti-nausea medicines
- Pain relievers
The purpose of these tests is find and treat cancer early. If you are aged 50 years and older, and are not at high risk, talk to your doctor to find the right test for you:
- Colonoscopy—every 10 years
- Sigmoidoscopy—every 5-10 years
- CT colonography—every 5 years
- Barium enema—every 5 years
- Stool DNA test every 3 years
- Fecal occult blood test (FOBT)—every year
- Fecal immunochemical test (FIT)—every year
Talk to your doctor about testing after age 40 if you are Black, Asian, or a native of Alaska.
Talk to your doctor about how often you should be tested if you have:
- People in your family with colon or rectal cancer, or polyps
- People in your family with inherited diseases of the colon or rectum
- Or had colon or rectal cancer, polyps
- Inflammatory bowel diseases
To help lower your chances of colon cancer:
American Cancer Society
United Ostomy Associations of America
Canadian Cancer Society
Ostomy Canada Society
Colorectal cancer. American Cancer Society website. Available at: https://www.cancer.org/cancer/colon-rectal-cancer.html. Accessed July 27, 2018.
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Colorectal cancer screening. EBSCO DynaMed Plus website. Available at:https://www.dynamed.com/topics/dmp~AN~T114074/Colorectal-cancer-screening. Updated May 21, 2018. Accessed July 27, 2018.
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Last reviewed May 2018 by EBSCO Medical Review Board Mohei Abouzied, MD, FACP Last Updated: 7/27/2018