General Information About Colon Cancer
Key Points for This Section
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Colon cancer is a disease in which malignant (cancer) cells
form in the tissues of the colon.
The colon is part of the
body’s digestive system. The
digestive system removes and processes nutrients (vitamins, minerals,
carbohydrates, fats, proteins, and water) from foods and helps pass waste
material out of the body. The digestive system is made up of the
esophagus,
stomach, and the
small and large
intestines. The first 6 feet of the
large intestine are called the large bowel or colon. The last 6 inches are the
rectum and the anal canal. The anal
canal ends at the anus (the opening
of the large intestine to the outside of the body).
Age and health history can affect the risk of developing colon
cancer.
Risk factors include the following:
Possible signs of colon cancer include a change in bowel habits
or blood in the stool.
These and other symptoms may be caused by colon cancer or by
other conditions. A doctor should be consulted if any of the following problems
occur:
- A change in bowel
habits.
- Blood (either bright red or very dark) in the
stool.
- Diarrhea, constipation, or feeling that the bowel does not
empty completely.
- Stools that are narrower than usual.
- General abdominal discomfort (frequent gas pains, bloating,
fullness, or cramps).
- Weight loss with no known reason.
- Constant tiredness.
- Vomiting.
Tests that examine the rectum, rectal tissue, and blood are
used to detect (find) and diagnose colon cancer.
The following tests and procedures may be used:
- Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
- Fecal occult
blood test: A test to check stool (solid waste) for blood that can only be seen with a microscope. Small samples of stool are placed on special cards and returned to the doctor or laboratory for testing.
- Digital rectal
exam: An exam of the rectum. The doctor or nurse inserts a lubricated, gloved finger into the rectum to feel for lumps or abnormal areas.
- Barium
enema: A series of x-rays of the lower gastrointestinal tract. A liquid that contains barium (a silver-white metallic compound) is put into the rectum. The barium coats the lower gastrointestinal tract and x-rays are taken. This procedure is also called a lower GI series.
- Sigmoidoscopy: A procedure to look inside the rectum and sigmoid (lower) colon for polyps, abnormal areas, or cancer. A sigmoidoscope (a thin, lighted tube) is inserted through the rectum into the sigmoid colon. Polyps or tissue samples may be taken for biopsy.
- Colonoscopy: A procedure to look inside the rectum and colon for polyps, abnormal areas, or cancer. A colonoscope (a thin, lighted tube) is inserted through the rectum into the colon. Polyps or tissue samples may be taken for biopsy.
- Biopsy: The removal of cells or tissues so they can be viewed under a microscope to check for signs of cancer.
- 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.
Certain factors affect prognosis
(chance of recovery) and treatment options.
The prognosis
(chance of recovery) 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.
- 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.
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