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.
Many cases of colon cancer have no symptoms. If there are symptoms, the following may indicate colon cancer:
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.
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:
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 outside the colon
Stage 0 colon cancer may be treated by removing the tumor. 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 (colectomy).
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 one type of medicine or a combination of medicines.
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:
Burning the cancer (ablation)
Delivering chemotherapy or radiation directly into the liver
Freezing the cancer (cryotherapy)
Targeted treatment zeroes in on specific targets (molecules) in cancer cells. These targets play a role in how cancer cells grow and survive. Using these targets, the drug disables the cancer cells so they cannot spread. Targeted therapy may be given as pills or may be injected into a vein.
You may have targeted therapy along with surgery, chemotherapy, or radiation treatment.
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.
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.
Cancer spreading to other organs or tissues (metastasis)
Development of a second primary colorectal cancer
When to Contact a Medical Professional
Call your health care provider if you have:
Black, tar-like stools
Blood during a bowel movement
Change in bowel habits
Unexplained weight loss
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 of colon cancer.
Some studies have reported that NSAIDs (aspirin, ibuprofen, naproxen, and celecoxib) may help reduce the risk of 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.
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Itzkowitz SH, Potack J. Colonic polyps and polyposis syndromes. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger & Fordtran’s Gastrointestinal and Liver Disease. 10th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 126.
National Cancer Institute. Colon Cancer Treatment – for health professionals (PDQ). Date last modified May 13, 2015. Available at: http://www.cancer.gov/types/colorectal/hp/colon-treatment-pdq. Accessed June 12, 2015.
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 Churchill Livingstone; 2014:chap 77.
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. Editorial update: 06/12/2015.