Colorectal Cancer Screening
Colorectal cancer (cancer in the colon or rectum) is a leading
cause of cancer deaths in the United States. But it doesn’t have to be.
When this cancer is found and removed early, the chances of a full
recovery are very good. Because colorectal cancer rarely causes symptoms
in its early stages, screening for the disease is important. It’s even
more crucial if you have risk factors for the disease. Learn more about
colorectal cancer and its risk factors. Then talk to your doctor about
being screened. You could be saving your own life.
Risk Factors for Colorectal Cancer
Your risk of having colorectal cancer increases if you:
Are 50 years of age or older.
Have a family history or personal history of colorectal cancer or adenomatous polyps.
Have a personal history of colorectal polyps, Crohn’s disease, or ulcerative colitis.
Have a family history of multiple concurrent solid-tumor cancers.
The Colon and Rectum
|A DRE can detect a growth in the rectum or anus. |
Waste from food you eat enters the colon from the small
intestine. As it travels through the colon, the waste (stool) loses
water and becomes more solid. Intestinal muscles push it toward the
sigmoid—the last section of the colon. Stool then moves into the rectum,
where it’s stored until it’s ready to leave the body during a bowel
How Cancer Develops
Polyps are growths that form on the lining of the colon or
rectum. Most are benign, which means they aren’t cancerous. But over
time, polyps can become malignant (cancerous). This occurs when cells in
these polyps begin growing abnormally. In time, malignant cells invade
more and more of the colon and rectum. The cancer may also spread to
nearby organs or lymph nodes or to other parts of the body. Finding and
removing polyps can help prevent cancer from ever forming.
Screening means looking for a medical problem before you have
symptoms. During screening for colorectal cancer, your doctor will ask
about your medical history, examine you, and do one or more tests.
History and Exam
Medical History: Your doctor will ask about your
medical history. Mention if a family member has had colon cancer or
polyps. Also mention any health problems you have had in the past.
Digital Rectal Exam (DRE): During a DRE, the doctor inserts a lubricated gloved finger into the rectum. The test is painless and takes less than a minute.
Fecal Occult Blood Test: This test checks for occult
blood in stool (blood you can’t see). Hidden blood may be a sign of
colon polyps or cancer. A small sample of stool is tested for blood in a
laboratory. Most often, you collect this sample at home using a kit
your doctor gives you. Follow the instructions carefully for using this
kit. Avoid certain foods and medications before the test, as directed.
Barium Enema with Contrast: This test uses x-rays to
provide images of the entire colon and rectum. Bowel prep is also
needed the day before this test. You will be awake for the test, but you
may be given medication to help you relax. At the start of the text, a
radiologist (a doctor who specializes in imaging tests) inserts a soft
tube into the rectum. The tube is used to fill the colon with a contrast
liquid (barium). The liquid helps the colon show up clearly on the
Virtual colonoscopy: This exam uses a series of
x-ray photographs to create a three-dimensional view of the colon.
During the procedure, you will lie on a table that is part of a special
x-ray machine called an MRI machine. A small tube will be
inserted into your rectum. Then, the table will move into the machine
and photos will be taken of your colon. A computer will combine these
photos to create a three-dimensional picture.
Colonoscopy: This is the best test doctors have
for finding and removing colorectal polyps. The day before the test, you
will do a bowel prep to cleanse your colon. You will be given
instructions for this. Just before the test, you are given a medication
to make you sleepy. Then, a long, flexible, lighted tube called a
colonoscope is gently inserted into the rectum and guided through the
entire colon. Images of the colon are viewed on a video screen. Any
polyps that are found are removed and sent to a lab for testing. If a
polyp can’t be removed, a sample of tissue is taken and the polyp is
removed later during surgery.
Sigmoidoscopy: This test is similar to
colonoscopy, but focuses only on the sigmoid colon and rectum. As with
colonoscopy, bowel prep must be done the day before this test. You are
awake during the procedure, but you may be given medication to help you
relax. During the test, the doctor guides a thin, flexible, lighted tube
called a sigmoidoscope through your rectum and lower colon. The images
are displayed on a video screen. Polyps are removed, if possible, and
sent to a lab for testing.
Risk and Complications of Scope Exams
When to Call Your Doctor After a Test
Call your doctor if you have any of the following after any screening test:
Fever over 101°F
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19067. All rights reserved. This information is not intended as a
substitute for professional medical care. Always follow your healthcare