Which test should I have to screen for colorectal cancer?
Introduction
Screening tests detect specific diseases before symptoms appear. Several tests can screen for colorectal cancer. Each test has its pros and cons. This information will help you understand your choices, whether you share in the decision-making process or rely on your doctor's recommendation.
Key points in making your decision
- Regular screening can greatly decrease your risk of dying from colorectal cancer.
- Regular screening is recommended for everyone age 50 and older.
- Screening tests look for colon polyps. Most cases of colorectal cancer begin as polyps. When polyps are found, they can be removed before they become cancer or while the cancer is in its early stages.
- Colorectal cancer rarely causes symptoms in the beginning. Symptoms such as bleeding from the rectum, a change in bowel habits, and weight loss usually occur later, when the cancer is harder to treat.
- You may need to begin screening at age 40 or earlier and be tested more often if you or members of your family have a history of colon polyps or colorectal cancer.
- You may need to begin screening earlier if you have Crohn's disease or ulcerative colitis.
Medical Information
What is colorectal cancer?
Colorectal cancer is the out-of-control growth of cells in the colon or rectum. These cells grow into masses, or tumors. Most colorectal cancers begin as polyps, which are growths attached to the inside of the colon or rectum. Colon polyps are common, but most of them do not turn into cancer. Some polyps are found with screening tests. With colonoscopy and sigmoidoscopy, polyps can be removed during the same procedures.
Colorectal cancer is the third most common cancer in men and women in the United States, and is the second leading cause of cancer deaths.1 It most often strikes people who are older than 50 who have no risk factors in their backgrounds other than their age.
For more information, see the topic Colorectal Cancer.
What are the symptoms of colorectal cancer?
Early-stage colorectal cancer rarely causes symptoms. Symptoms of colorectal cancer usually occur later, when the cancer is are harder to treat. Common symptoms include:
- Pain in the abdomen.
- Blood in your stool or black, tarry stools.
- A change in your bowel habits (such as very narrow stools or frequent diarrhea or constipation).
- Unexplained weight loss.
- Constant fatigue.
Why is regular screening important?
Most colorectal cancer cases can be prevented by having regular screening tests and having polyps removed. Survival rates are higher when colorectal cancer is found and treated early before it spreads to lymph nodes or other organs.
Why is my family's history important?
You are twice as likely to get colorectal cancer if one of your parents, brothers, sisters, or children has had it, especially if that person was diagnosed before the age of 50. The two most common inherited causes of colorectal cancer are familial adenomatous polyposis (FAP) and hereditary nonpolyposis colon cancer (HNPCC). Most people with these conditions will develop colorectal cancer if they are not treated.
If you have any of these conditions in your background, you will need to be screened at an earlier age—and have more frequent screening—than other people.
For more information, see the topic Colorectal Cancer.
Your Information
Several tests are available to screen for colorectal cancer:
- Stool tests. These include:
- A fecal occult blood test (FOBT), every year.
- A fecal immunochemical test (FIT), every year.
- A stool DNA test (sDNA). Experts have not yet set guidelines for how often this test should be done.2
- Barium enema, usually done every 5 years.
- Flexible sigmoidoscopy, usually done every 5 years.
- A stool test each year and a flexible sigmoidoscopy every 5 years.
- Colonoscopy, usually done every 10 years.
- Computed tomographic colonography (CTC), also known as virtual colonoscopy, possibly done every 5 years. Experts have not yet set guidelines for how often this test should be done.2
Flexible sigmoidoscopy (also called a sigmoidoscopy or shortened to "flex sig") and colonoscopy are done in doctor's offices, clinics, and hospitals. A barium enema is done in a hospital or outpatient radiology department.
Complications from barium enema, colonoscopy, or sigmoidoscopy include damage to or puncture of the colon. These complications are rare, but are somewhat more common with colonoscopy than with virtual colonoscopy, barium enema, or sigmoidoscopy. Colonoscopy and barium enemas are not recommended for pregnant women, although a colonoscopy can be done if needed.
The decision about choosing a test for colorectal cancer screening takes into account your personal feelings and the medical facts.
Pros and cons of colorectal cancer screening tests
Stool tests (FOBT, FIT, and sDNA) Reasons to have a stool test Reasons not to have a stool test
- Increases the chance that cancer will be detected early
- Can be done at home
- Does not require sedation
- Does not cause discomfort
- May be the least expensive test
Are there other reasons you might want to choose a stool test?
- Cannot, by itself, be used to diagnose colon polyps or colon cancer
- If the test is positive, you may need other tests anyway.
- It is not as reliable for finding colon cancer as other tests.
Are there other reasons you might not want to choose a stool test?
Barium enema Reasons to have a barium enema Reasons not to have a barium enema
- Provides a good view of the entire colon
- Is accurate for finding abnormalities, such as narrowed areas or pockets or sacs in the intestinal wall
- Does not require sedation
- Is less expensive than colonoscopy
Are there other reasons you might want to choose barium enema?
- Some polyps and cancer can be missed
- Polyps cannot be removed during the procedure.
- Cannot be used during pregnancy
- Requires liquid diet and bowel preparation beforehand
- Can be uncomfortable
Are there other reasons you might not want to choose barium enema?
Sigmoidoscopy Reasons to have a sigmoidoscopy Reasons not to have a sigmoidoscopy
- Is less expensive than colonoscopy
- Is accurate for finding polyps in the lower part of the colon (where most polyps occur)
- Small polyps that are found can usually be removed at the same time.
- Usually does not require sedation
Are there other reasons you might want to choose sigmoidoscopy?
- Does not examine the upper section of the colon
- Requires bowel preparation (enema)beforehand
- Can be uncomfortable
- Risk of complications
Are there other reasons you might not want to choose sigmoidoscopy?
Colonoscopy Reasons to have a colonoscopy Reasons not to have a colonoscopy
- Can both detect and remove polyps in the entire colon during the same exam
- May be needed if a polyp or other abnormality is found during either barium enema or sigmoidoscopy, or if a stool test is positive
- Does not usually cause a lot of discomfort during the procedure, because you will be sedated for colonoscopy
- Is usually only needed every 10 years
Are there other reasons you might want to choose colonoscopy?
- Requires liquid diet and bowel preparation beforehand
- May require sedation and time off from work
- Not recommended during pregnancy, although it can be done if needed
- May be an expensive test
- Risk of complications
Are there other reasons you might not want to choose colonoscopy?
Computed tomographic colonography (CTC) Reasons to have a CTC Reasons not to have a CTC
- Provides a good view of the colon as well as the upper and lower belly
- Is less invasive than a colonoscopy
- Usually does not require sedation
- Less risk of complications than a colonoscopy
Are there other reasons you might want to choose CTC?
- Requires liquid diet and bowel preparation beforehand
- Polyps cannot be removed during the test
- Exposure to X-rays
- May be an expensive test
Are there other reasons you might not want to choose CTC?
These personal stories may help you make your decision.
Wise Health Decision
Use this worksheet to help you make your decision. After completing it, you should have a better idea of how you feel about having a screening test for colorectal cancer. Discuss the worksheet with your doctor.
Circle the answer that best applies to you.
I am worried about having discomfort during a colonoscopy, sigmoidoscopy, or barium enema. Yes No Unsure I want to have the test that is going to see as much as possible. Yes No Unsure I'd rather have one test every 10 years than another test every 5 years. Yes No Unsure I prefer a test that I can do by myself at home. Yes No Unsure I do not want to miss any work to do this test. Yes No Unsure If I have a sigmoidoscopy or barium enema, I will be able to go back to work the same day. Yes No Unsure I don't want to have two procedures; I would rather my doctor remove any polyps I might have at the same time that I have a colonoscopy. Yes No Unsure I do not have health insurance and cannot afford the cost of the test. Yes No Unsure My health insurance won't pay for a colonoscopy but will pay for another type of test. Yes No Unsure I am worried about the risk of puncturing or damaging my colon during a colonoscopy. Yes No Unsure Use the following space to list any other important concerns you have about this decision.
What is your overall impression?
Your answers in the above worksheet are meant to give you a general idea of where you stand on this decision. You may have one overriding reason for making your choice.
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| Author: | Bets Davis, MFA | Last Updated: December 1, 2006 |
| Medical Review: | Anne C. Poinier, MD - Internal Medicine Arvydas D. Vanagunas, MD - Gastroenterology | |
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