Colon Cancer

Medically reviewed by: Gary H. Hoffman, MD

Each year, colon cancer afflicts 150,000 Americans and causes 50,000 deaths, making it the third most prevalent form of cancer in the United States. However, with modern methods of treatment and prevention, many deaths caused by colon cancer can be avoided. The key to preventing  colon cancer casualties is detection, diagnosis and treatment in the early stages of the disease.  In fact, since polyps are the precursors of colon and rectal cancer, removing polyps before they become malignant is potentially life saving.

Also known as colorectal cancer or bowel cancer, colon cancer begins as pre-cancerous growths, also known as polyps, in the large intestine (colon) or rectum (the end of the colon).


The majority of colon cancer cases begin as abnormal growths, or polyps on the bowel wall.  Though most polyps are benign in the beginning, they can grow in size and become cancerous over time.

Colon cancer stems from genetic damage that prevents the proper growth and normal death of cells in the colon. Often, this damage is a result of lifestyle factors, but may also be due to aging. Lifestyle factors that may contribute to increased risk of colon cancer may include the following:

  • Diet high in fat and low in fiber
  • Diet low in fruit and vegetables
  • Sedentary lifestyle or lack of exercise
  • Obesity or overweight
  • Consumption of alcohol
  • Use of tobacco

If you have suffered from inflammatory bowel disease, colon polyps or cancer in other organs (particularly the uterus or breast), the risk of developing colon cancer may be increased.

A family history of colon cancer will also increase your risk of getting the disease. In an estimated 5 percent of cases, colon cancer stems from a passed down genetic mutation and may recur in multiple generations. Inherited varieties of colon cancer include:

  • Hereditary Non-polyposis Colorectal Cancer (HPNCC). This syndrome accounts for approximately 3 percent of all colon cancer cases, and 80 percent of those with HPNCC will develop colorectal cancer. As the word “non-polyposis” suggests, HPNCC is characterized by its lack of polyps. Because the mutation exists in all of the body’s cells, other organs may develop cancer as well. If three relatives have had colon cancer, or two successive generations have suffered from the condition, genetic testing for HPNCC is recommended.
  • Familial Adenomatous Polyposis (FAP). This syndrome accounts for two percent of all colon cancer cases. Almost every individual with FAP will develop colon cancer by the age of 40. FAP is characterized by the formation of hundreds, if not thousands of polyps in the colon, stomach and small intestine. FAP can also lead to duodenal cancer (the second leading cause of FAP-related deaths) and cancers in other organs. Polyps often begin forming when the individual is a teenager, and these polyps may not all be able to removed due to their their large numbers lining the colon and rectum. However, in patients who have not yet demonstrated polyp growth, regular screenings are recommended to watch for the onset of polyposis.  Like HPNCC, FAP is usually diagnosed with a careful examination of a patient’s family history.  Once the polyps are seen and a diagnosis of FAP is obtained, an operation is usually recommended.


Though you should begin screening at a younger age if at a higher risk of developing colon cancer, it is recommended that all individuals begin receiving regular screenings for colon cancer at the age of 50.

Recommended intervals for the methods of colon cancer screenings are as follows:

  1. Fecal occult blood test (FOBT), in which three consecutive stool samples are checked for blood, once each year. This is combined with flexible sigmoidoscopy (below) and is the least reliable of all screening methods.
  2. Flexible sigmoidoscopy is an in-office procedure in which a lighted, flexible tube called a flexible sigmoidoscope is used to inspect the rectum’s interior walls and part of the sigmoid colon. This is combined with fecal occult blood testing. Finding of polyps necessitates proceeding with a colonoscopy to evaluate the entire colon.
  3. Colonoscopy, performed in an outpatient center, is a procedure in which a lighted, flexible tube called a colonoscope is used to inspect the rectum’s interior walls and the entirety of the colon, once every 5 years. During a colonoscopy, polyps may also be removed, and tissue samples may be collected for further examination. Colonoscopy is also used as a diagnostic test when an individual exhibits symptoms of colon cancer.
  4. Barium enema, is an x-ray in which a thin paste of barium is introduced into the rectum and lines the walls of the entire colon looking for abnormalities of the colon or rectal walls. Any abnormalities or suspicion for polyps need to be investigated further with colonoscopy.
  5. Virtual colonoscopy is a CT scan looking at the inside of the colon.  If abnormalities are found, a colonoscopy will be required.

Eating a diet that is high in fiber and low in fat may also play a role in the prevention of colon cancer, though this has not been definitively proven.


Because colon cancer typically begins as benign polyps, it often does not produce symptoms in its early stages and can develop unnoticed. This makes regular examination a necessity for early detection.

Rectal bleeding or changes in bowel movements like diarrhea or constipation can be indicative of colon cancer and may warrant examination. The later stages of the disease are typically accompanied by symptoms like weight loss and abdominal pain, often indicating that the disease has become extensive.


In almost all cases of colon cancer, surgery is required, though chemotherapy and radiation treatments may also be employed. The operation to remove the cancer can be performed laparoscopically, or using a surgical robot (also know as robotic surgery), or with a longer, open incision.  If colon cancer is detected and treated in its early stages, between 80 and 90 percent of colorectal cancer patients recover. The cure rate drops to less than 50 percent if rectal or colon cancer is not diagnosed until its later stages.

Because people who have colon cancer may develop the disease a second time, it’s important to maintain regular screenings and checkups. You should contact your colorectal specialist immediately if you experience any health issues or worsening symptoms between checkups. Due to the fact that colon cancer is often hereditary, screening of family members is also prudent if you have been diagnosed with colon cancer.

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