Colon Cancer Facts & Risk Factors

Colon Cancer Facts & Risk Factors

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Colorectal Cancer

What is it?How common is it?Risk FactorsHow can you prevent it?
  • Colorectal, or colon cancer usually begins with the development of benign colonic polyps. Polyps form when cells lining the colon grow, divide and reproduce in an unhealthy, disorderly way, producing a growth.
  • These polyps can be cancerous and can spread to other parts of the body by invading the colon wall and the surrounding blood vessels.
  • Colorectal cancer often begins with no symptoms.
  • Colon cancer is the second leading cancer killer in the U.S., and the third most common cancer overall.
  • This year, approximately 131,600 new cases will be diagnosed.
  • Eighty to 90 million Americans (or 25 percent of the U.S. population) are considered at risk for colon cancer because of age or other factors.
  • Men and women aged 50 and older are at almost equal risk of developing colorectal cancer.
  • Those who have a personal or family history of colorectal neoplasia (cancer or polyps) are at high risk of developing the disease.
  • Anyone who has a personal history of inflammatory bowel disease, such as ulcerative colitis or Crohn’s disease, is also at high risk.
  • Know your family history. Genetic factors may determine a person’s susceptibility to the disease, whereas dietary and other lifestyle factors may determine which at-risk individuals actually go on to develop the disease.
  • See your doctor for yearly screenings if you are aged 50 or older.
  • Maintain a diet low in animal fat and high in fruits, vegetables and fiber
  • Exercise regularly.
  • Prevent obesity.
  • Avoid cigarette smoking.

Diagnosis of Colorectal Cancer


Screening tests help find polyps or cancer at a precancerous stage or early stage before symptoms arise. Finding and removing polyps most likely prevent colorectal cancer. Treatment for colorectal cancer is very effective when the disease is found early.

The following screening tests can be used to detect polyps and cancer:
  • Fecal occult blood test (FOBT): Sometimes cancers or polyps bleed, and the FOBT can detect tiny amounts of blood in the stool. If this test detects blood, other tests are needed to find the source of the blood.
  • Digital rectal exam: A rectal exam is often part of a routine physical examination. A lubricated, gloved finger is inserted into your rectum to feel for abnormal areas and detect any blood in the stool.
  • Sigmoidoscopy: Rectum and the lower part of the colon are checked with a lighted tube called a sigmoidoscope. If polyps are found, they are removed. The procedure to remove polyps is called a polypectomy.
  • Colonoscopy: The inside of the rectum and entire colon are examined using a long, lighted tube called a colonoscope. If polyps are found, they are removed. A biopsy is done if abnormal tissue is found inside the colon.
  • Virtual colonoscopy: A procedure that uses a series of x-rays called computed tomography to make a series of pictures of the colon. A computer puts the pictures together to create detailed images that may show polyps and anything else that seems unusual on the inside surface of the colon. This test is also called colonography or CT colonography.
  • Double-contrast barium enema: An enema with a barium solution is given and air is pumped into the rectum. Several x-ray pictures are taken of the colon and rectum. Polyps or tumors may show. This procedure is considered if a patient is unable to undergo a colonoscopy. If an abnormality is detected by barium enema, then a colonoscopy is needed to either remove it or to do a biopsy.

If tests results show an abnormal finding, such as a polyp, a biopsy to check for cancer cells is  necessary. Often, the abnormal tissue can be removed during colonoscopy or sigmoidoscopy. A pathologist checks the tissue for cancer cells using a microscope.

Colorectal Cancer Symptoms

The most common symptoms are:

  • Having diarrhea or constipation
  • Feeling that your bowel does not empty completely
  • Finding blood (either bright red or very dark) in your stool
  • Finding your stools are narrower than usual
  • Frequent gas pains or cramps, or feeling bloated
  • Weight loss with no known reason
  • Feeling very tired all the time
  • Nausea or vomiting

However, colon cancer in early stages may not produce any symptoms; this is why screening for colon cancer is necessary to detect cancer at an early stage.

Staging of Colorectal Cancer

As soon as the cancer is diagnosed, it is important to know the extent (stage) of the disease to plan the best treatment. The stage is based on whether the tumor has invaded nearby tissues, whether the cancer has spread and, if so, to what parts of the body.

The following tests may be done to find out the stage of the cancer:
  • Colonoscopy: colonoscopy is performed for diagnosis and to find the extent of the disease.
  • CT scan: An x-ray machine linked to a computer takes a series of detailed pictures of areas inside your body. You may receive an injection of dye. A CT scan may show whether cancer has spread to the liver, lungs, or other organs.
  • Endorectal ultrasound: An ultrasound probe is inserted into the rectum. The probe sends out sound waves that bounce off the rectum and nearby tissues, and a computer uses the echoes to create a picture. The picture may show how deep a rectal tumor has grown or whether the cancer has spread to lymph nodes or other nearby tissues.
The Stages of colorectal cancer:
  • Stage 0: The cancer is found only in the innermost lining of the colon or rectum. Carcinoma in situ is another name for Stage 0 colorectal cancer.
  • Stage I: The tumor has grown into the inner wall of the colon or rectum. The tumor has not grown through the wall.
  • Stage II: The tumor extends more deeply into or through the wall of the colon or rectum. It may have invaded nearby tissue, but cancer cells have not spread to the lymph nodes.
  • Stage III: The cancer has spread to nearby lymph nodes, but not to other parts of the body.
  • Stage IV: The cancer has spread to other parts of the body, such as the liver or lungs.
  • Recurrence: This is cancer that has been treated and has returned after a period of time when the cancer could not be detected. The disease may return in the colon or rectum, or in another part of the body.

Treatment of Colon and Rectal Cancer:

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis depends on the following:

  • The stage of the cancer (whether the cancer is in the inner lining of the colon only, involves the whole colon, or has spread to other places in the body).
  • Whether the cancer has blocked or created a hole in the colon.
  • Whether there are any cancer cells left after surgery.
  • The blood levels of carcinoembryonic antigen (CEA; a substance in the blood that may be increased when cancer is present) before treatment begins.
  • Whether the cancer has recurred.
  • The patient’s general health.

Treatment options depend on the following:

  • The stage of the cancer.
  • Whether the cancer has recurred.
  • The patient’s general health.

Stage I Colon Cancer

  • Treatment of stage I colon cancer is usually surgical resection

Stage II Colon Cancer

  • Treatment of stage II colon cancer may include the following:
  • Surgical resection
  • Clinical trials of chemotherapy or biologic therapy after surgery.

Stage III Colon Cancer

  • Surgical resection followed by chemotherapy.
  • Clinical trials of chemotherapy after surgery.

Stage IV and Recurrent Colon Cancer

  • Chemotherapy and targeted therapy with a monoclonal antibody.
  • Surgical resection of the primary tumor in certain cases
  • Surgery to remove parts of other organs, such as the liver, lungs, and ovaries, where the cancer may have recurred or spread. Hepatic chemoembolization, radiofrequency ablation or cryosurgery.
  • Radiation therapy may be offered to some patients as palliative therapy to relieve symptoms and improve quality of life.
  • Clinical trials of chemotherapy and/or targeted therapy with a monoclonal antibody.

Rectal Cancer

  • The main difference in the treatment of rectal cancer that is different from colon cancer is incorporation of a combination of chemotherapy and radiation therapy before or after surgery.

*Source: National Cancer Institute