FCMS
Friday May 08, 2009 
Colon Cancer - Prevention and Early Detection English | 中文 
COLON CANCER
Cancer of the large intestine (colon cancer) is a common cancer in people over age 50, affecting about 1 in 20 people in North America. Early detection is important since early treatment improves the chance of complete cure.
CAN COLON CANCER BE PREVENTED?
Although the cause of colon cancer is still unknown, there is evidence that most of these cancers arise frompolyps (benign intestinal tumors). Some polyps change slowly into cancer over a period of several years. The discovery and removal ofpolyps before they transform into cancer is one of the most effective ways to prevent colon cancer.

Dietary fat intake is believed to play a role based on wide differences in the cancer patterns in different parts of the world. For example, the incidence of colon cancer is much higher in North America than in China, and the Chinese who migrate to North America have a higher incidence of colon cancer. A diet high in fiber (rich in vegetables, fruits, and whole grains) and low in fat reduces the risk of developing colon cancer.

Risk Factors for colon cancer:
  1. family history of colon cancer

  2. history of polyps

  3. people with longstanding chronic inflammatory bowel disease (ulcerative colitis or Crohn´s disease involving the colon) Familial polyposis coli, a rare hereditary disease which affects many members of the same family.
EARLY DETECTION OF COLON CANCER:
  1. Early Recognition of Symptoms of colon cancer: It is important for people to know and recognize the possible signs of colon cancer so that early diagnosis is possible.

    • A change in bowel habit - e.g. increasing constipation, or irregular bowel habit with alternating constipation and diarrhea is the most common symptom. Consult a doctor for any unexplained change in the pattern of bowel action which lasts more than 2 weeks.

    • Blood in stool or bleeding from rectum may be a symptom of bowel cancer and should not be assumed to be caused by hemorrhoids, although common. Very small amounts of blood may not be visible but can be detected by a stool test for occult blood. Blood loss over a long period of time may result in anemia, with symptoms of paleness and fatigue.

    • Feeling of incomplete evacuation of the bowels which is persistent, and associated with little passage of stools, may suggest a tumor low in the rectum.

    • Change in stool caliber (e.g. very narrow like a pencil).

    • Crampy abdominal pain or discomfort

    Note: symptoms that have been present unchanged for many years are usually not the result of cancer.

  2. Surveillance for colon cancer: Detection and removal of very early cancers or polyps, while symptoms have not yet appeared, is highly successful in preventing or curing colon cancer in these individuals.

    • People at high risk of developing colon cancer (see risk factors above) should be followed by their doctor for annual check-ups, including colonoscopy or Barium Enema (for total colon examination) at regular intervals.

    • All people 50 years or older with normal risk can be screened for early detection of colon cancer by seeing their doctor for rectal examination and examination of stools for occult blood (yearly), and sigmoidoscopy every 5 years.
DIAGNOSTIC EXAMINATION AND TESTS:
A combination of the following examinations may be used in diagnosing colon cancer.
  1. Rectal Examination

    This is done by a physician by inserting a gloved finger into the rectum, and is a normal part of a complete physical examination.

  2. Test for Occult Blood in the stool

    It is possible to check for the presence of occult (or hidden) blood in the stool which is not visible to the eye. Small samples of stool collected at home are checked chemically for the presence of blood, which can be identified in minute quantities.

    A positive test does not mean that cancer is definitely present (since the test is not specific for cancer) but that more precise tests should be done.

  3. Sigmoidoscopy

    A short, hollow instrument bearing a light, called a sigmoidoscope, is inserted into the large intestine from below by the physician. This allows a careful visual examination of the interior of the large intestine up to about 12 inches, and provides the opportunity for a biopsy to be taken if necessary. (A biopsy is a small piece of tissue that can be examined under a microscope in order to give a precise diagnosis.)

    This test can be done in a doctor's office without the need for an anesthetic and with minimal discomfort.

  4. Colonoscopy

    A long instrument which is flexible with a special light using fiberoptics can be inserted from below (similar to a sigmoidoscopy) to examine the interior of the large intestine.

    This test, which is done by a specially trained physician, gives the most thorough examination of the entire colon as well as the opportunity for biopsies, if necessary.

  5. Barium Enema

    This is an X-ray of the large intestine using a dense substance called Barium to fill the interior of the entire colon (given as an enema). Barium gives contrast to allow abnormalities in the lining of the bowel to show up on the X-ray.

    Treatment for colon cancer, which includes surgery, radiotherapy, and chemotherapy (used singly or in combination) are highly effective and can result in cure if the cancer is diagnosed before spread has occurred.


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