The colon, or the large intestine, is at the
end of the digestive system. Its primary function is to desiccate
(dry), package, and store the waste left over after food is digested
and absorbed by the small intestine. The colon very efficiently
absorbs water and reduces the volume of waste that needs to be eliminated
in the stool in a convenient form at a convenient time.
Cancer of the colon and rectum - called colorectal cancer (CRC)
- is the second leading cause of cancer deaths among men and women
in the United States. However, if detected early, colorectal cancer
can be cured. With simple preventive steps, you can greatly reduce
your risk of developing the disease. It is important for you to
understand your risks for colorectal cancer, the symptoms, and
screening tests that can detect cancerous growths.
Colorectal cancer develops from non-cancer polyps called adenomatous
polyps. A polyp is a grape-like growth on the inside wall of the
colon or rectum. Polyps grow slowly over three to ten years. Most
people do not develop polyps until after the age of 50. Some polyps
become cancerous, others do not. In order to prevent colorectal
cancer, it is important to get screened to find out if you have
polyps, and to have them removed if you do. Removal of polyps
has been shown to prevent CRC.
How Do I Know if I’m at Risk for Colorectal
Everyone has a risk of developing CRC. However, your risk depends
on several factors.
You are at average risk for colorectal cancer if you:
- Are age 50 or older and have no other risk factors.
You are at increased risk for colorectal cancer if you:
- Have a personal history of CRC or adenomatous polyps
- Have a family history - one or more parents, brothers and/or
sisters, or children - of CRC or adenomatous polyps
- Have a family history of multiple cancers, involving the breast,
ovary, uterus, and other organs
- Have a personal history of inflammatory bowel disease, such
as ulcerative colitis or Crohn’s Disease
There are several inherited disorders that greatly increase your
risk of CRC. However, they are not very common.
Other factors that increase your risk of developing CRC are:
- A diet that is low in fiber and high in fat
- A sedentary lifestyle
Aren’t Women at Less Risk for Colorectal
Cancer than Men?
Men and women are equally affected by colorectal cancer. In
fact, colorectal cancer is the third leading cause of cancer death
in women. Also, about 67,000 women are diagnosed with this cancer
each year and more than 40 percent of them - 28,600 - die from
What are the Symptoms of Colorectal Cancer?
Colorectal cancer begins with no symptoms at all. However, over
time, there are a number of warning signs:
- Rectal bleeding
- Blood in your stool (bright red, black, or very dark)
- A change in your bowel movements, especially in the shape
of the stool (e.g., narrow like a pencil)
- Cramping pain in your lower abdomen
- Frequent gas pains
- Discomfort in or the urge to move your bowels when there is
- Weight loss without dieting
- Constant fatigue
What Should I Do if I Have These Symptoms?
Call your doctor and schedule an appointment. Only your physician
can determine if your symptoms are due to CRC.
Why is Screening Important If I have No Symptoms?
Screening is important for two reasons. The early stage of CRC
- which is when it is most curable - frequently does not cause
any symptoms. And, just as important, screening is the only way
to find polyps. If the polyp is removed, it cannot develop into
What Type of Screening Tests are Available?
There are several types of screening tests. Talk with your doctor
about which one is best for you. People at average risk should
start screening at age 50. People at increased risk start at age
- Digital rectal examination: In this test, the doctor manually
inserts a gloved finger into the rectum to feel for abnormalities.
While this test is easy to do, it is not very effective.
- Fecal occult blood test (FOBT): In this procedure, the stool
is tested for the presence of blood that is invisible to the
eye. The test is available in a kit and can be taken at home
to collect stool samples. The stool cards can be mailed to your
doctor. This test is relatively easy and inexpensive, however,
many factors can interfere with its accuracy. This test is recommended
annually for persons beginning at age 50 for people at average
- Sigmoidoscopy: Your doctor will use
a long, flexible, lighted tube to check the rectum and the lower
part of the colon for polyps and cancer. If a polyp is found,
it can be sampled through the scope and sent to a lab to be
tested. This test can be performed in a doctor’s office,
and does not require any anesthesia or sedation, but does require
limited preparation such as an enema. Insertion of the tube
may be somewhat uncomfortable, and some cramping may occur during
the procedure, which takes about ten minutes. After the test,
there may be some mild abdominal gas pains. If the doctor took
a biopsy, some traces of blood may be in the stool for a few
days. This test is recommended every five years beginning at
age 50 for people at average risk.
- Colonoscopy: This procedure
is done by a gastroenterologist. He or she will use a long,
flexible, lighted tube - called the colonoscope - to view the
entire colon and rectum for polyps or cancer. A bowel cleansing
preparation of the colon is required before the procedure. The
colonoscope has a camera at the end, which can project images
on a TV screen. If a polyp is found, it can be removed by a
wire loop that is passed through the colonoscope and is hooked
around the base of the polyp. The doctor sends an electric current
through the loop, which severs the polyp from the colon wall
and pulls it out of the colon. The polyp is then sent to a laboratory
to be tested to determine if it is cancerous. This procedure
requires patients to be sedated, and usually takes about 20
minutes. There is some pressure that can be felt from the instrument’s
movements and some cramping afterwards, but this is usually
all that occurs. Some traces of blood may be in the stool for
several days after the procedure if a biopsy was taken.
- Barium enema: This test is
an X-ray examination of the entire colon and rectum and may
be done instead of a colonoscopy. After cleansing of the colon,
a soft, flexible tube is inserted into the rectum and a liquid
called barium is inserted into the tube. Special X-rays follow
the flow of the barium in the colon and outline any lumps, polyps,
or abnormalities. A person may feel some cramping and a strong
urge to defecate during the test. This procedure is recommended
as a substitute for colonoscopy every ten years.
How Do I Prepare for These Screening Tests?
Proper preparation is the most important thing you can do to
help ensure you get the most accurate screening possible. Your
doctor will give you complete instructions on what to do. Before
any test, let your doctor know about any medicines you are taking
because they may affect the test results.
What if I Am Diagnosed with Colorectal Cancer?
If you are diagnosed with CRC, surgery is generally required
to remove the cancerous polyps and other malignant tissue. The
type of surgery and follow-up treatment will depend on how far
advanced the cancer is. In the past, a colostomy was usually necessary.
However, new surgical technologies can eliminate the need for
a colostomy in many patients.
How Can Colorectal Cancer be Prevented?
There is no way to completely eliminate the risk of developing
CRC. That is why screening is so important. However, there is
evidence that you can reduce your chance of getting CRC by doing
- Have a diet that is rich in fiber; eat plenty of whole grains,
fruits, and vegetables
- Eat cabbage, broccoli, cauliflower, and brussel sprouts often
- Avoid foods that are high in fat, particularly saturated fat
- Eat foods that are high in calcium
- Exercise regularly
Researchers are also investigating the possibility that some
drugs such as aspirin, ibuprofen, calcium supplements, folic acid
and others may help prevent colorectal cancer.