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Colon Cancer: Which Screening Test Should I Have?

You may want to have a say in this decision, or you may simply want to follow your doctor's recommendation. Either way, this information will help you understand what your choices are so that you can talk to your doctor about them.

Colon Cancer: Which Screening Test Should I Have?

Get the facts

Your options

  • Get a stool test, such as a fecal occult blood test (FOBT), every year.
  • Get a sigmoidoscopy every 5 years.
  • Get a colonoscopy every 10 years.

Key points to remember

  • Screening tests find health problems early, before symptoms appear. Regular testing to find colon cancer early is very important because as soon as there are symptoms, it's usually too late to cure colon cancer.
  • Regular testing lowers your risk of dying from colon cancer.
  • The two main types of tests are:
    • Those that mostly find signs of colon cancer (stool tests).
    • Those that can also help prevent colon cancer by finding polyps before they turn into cancer (sigmoidoscopy and colonoscopy). And if you have a sigmoidoscopy or colonoscopy, any polyps that are found usually can be removed during the test.
  • Routine testing is recommended for everyone age 50 and older who has a normal risk for colon cancer. Your doctor may recommend earlier or more frequent testing if you have a higher risk for colon cancer.
FAQs

What is colorectal cancer?

Colorectal cancer happens when cells that are not normal grow in your colon or rectum. Most people just call it "colon cancer."

These cancers usually begin as polyps, which are growths attached to the inside of the colon or rectum. Colon polyps are common, and most of them do not turn into cancer. Polyps are found during some screening tests. And polyps found during a colonoscopy or sigmoidoscopy usually can be removed at the same time.

Why is regular screening important?

When colon cancer is found early through screening tests, it is more easily treated.

Screening tests can detect or prevent this cancer, but only about half of people older than 50 are screened. According to the American Cancer Society, if everyone were tested, tens of thousands of lives could be saved each year.

Why is your family history important?

A family history of colon cancer makes you more likely to get it. You will need to be screened at an earlier age—and have more frequent screening—than other people if:

  • You have a close relative with colon cancer. You are more likely to get colon cancer if:
    • One of your parents, brothers, sisters, or children had it before the age of 60.
    • Two or more of your parents, brothers, sisters, or children has had it at any age.
  • You have a family history of certain colon problems, such as familial adenomatous polyposis (FAP) or hereditary nonpolyposis colon cancer (HNPCC). Most people who inherit these conditions will get colon cancer if they are not screened and treated.

What are stool tests?

Stool tests involve sending some of your stool to a lab for testing to see if there is evidence of cancer. They don't help prevent colon cancer, but they do help find it early, when it is more treatable.

Stool tests need to be done once a year to find colon cancer as early as possible. These tests can usually be done in the privacy of your home.

There are three types of stool tests:

  • Fecal occult blood test (FOBT). This is the most common stool test. You put tiny samples of your stool on a special card or cloth and send it to a lab. The lab uses certain chemicals to find blood that you can't see with the naked eye. FOBT tests don't cost much.
  • Fecal immunochemical test (FIT). This is a newer test that is a little easier to do at home. It costs more than an FOBT.
  • Stool DNA test (sDNA). This is the newest stool test. It looks for changes in DNA (genetic material) in the stool. It costs the most.

If you can't or won't go to the doctor to get an at-home stool test, you can check your local drugstore for an over-the-counter brand. But you may feel better if you talk to your doctor about what the test results mean.

Risks of stool tests

There is no risk involved in the actual use of a stool test. But there are some things you need to think about:

  • Blood in the stool can be a sign of colon cancer, but it's more often caused by something else, such as hemorrhoids, ulcers, or taking aspirin. These other conditions can cause a "positive" result even when you don't have cancer.
  • If your test is positive, you will probably need to have a colonoscopy.
  • Unlike other tests, stool tests don't help prevent cancer by finding colon polyps before they turn into cancer. Stool tests mostly find cancer that is already present.

What is flexible sigmoidoscopy?

Flexible sigmoidoscopy (say "sig-moy-DAW-skuh-pee") is a test that lets your doctor look at the inside of the lower part of your colon. The doctor looks through a lighted tube that can bend around the corners of the colon.

With this test, the doctor can find polyps in the lower part of your colon and may be able to remove them. Polyps are growths inside the colon that can turn into colon cancer.

When used to screen for colon cancer, this test is usually done every 5 years.

Getting ready for a sigmoidoscopy involves cleaning out the colon:

  • For 1 to 2 days before the test, you may be on a clear liquid diet.
  • You will likely have an enema before the test.

This test usually takes 5 to 15 minutes or slightly longer if polyps are found and removed.

Risks of sigmoidoscopy

There is very little risk of problems from having a sigmoidoscopy.

  • There is a slight chance of piercing the colon (perforation) or causing severe bleeding by damaging the wall of the colon. But this is rare.
  • There is also a slight chance of a colon infection (very rare).

A sigmoidoscopy only looks at the lower part of your colon, which is where most polyps grow. But sometimes polyps grow in the upper part of your colon, and they would not be seen with this test.

If your doctor finds polyps during a sigmoidoscopy, you may need to have a colonoscopy to see if there are more polyps farther up in your colon.

What is colonoscopy?

Colonoscopy (say "koh-luh-NAW-skuh-pee") is a test that lets your doctor look at the inside of your entire colon. The doctor looks through a lighted tube that can bend around the corners of the colon.

With this test, the doctor can find and remove polyps, which are growths inside the colon that can turn into colon cancer.

When used as a screening test for colon cancer, this test is usually done every 10 years. If you have a colonoscopy, you won't need to have a yearly stool test. A colonoscopy may be done more often if your risk is higher than average.

Getting ready for a colonoscopy involves a very thorough cleansing of the colon, which must be completely empty:

  • For 1 to 2 days before the test, you will be on a clear liquid diet.
  • On the night before the test, your doctor may have you take a prescription laxative tablet or drink a laxative solution. This will make you use the bathroom often.

You may be given medicine to help you relax. Many people don't even remember the test afterward because they are so relaxed.

The test usually takes 30 to 45 minutes, but it may take longer if polyps are found and removed.

Risks of colonoscopy

The scope or a small tool may tear the lining of the colon or cause bleeding. Although these problems are rare, they happen more often with colonoscopy than with sigmoidoscopy.

Virtual colonoscopy

A virtual colonoscopy uses pictures taken during a CT scan to look at the colon. With this procedure, a thin tube is inserted into the rectum and air is pumped through the tube into the colon. The air expands your colon so that it is easier to see on an X-ray. If you are interested in learning more about virtual colonoscopy, talk to your doctor.

Getting ready for a virtual colonoscopy involves the same thorough cleansing of the colon that is needed for a regular colonoscopy:

  • For 1 to 2 days before the test, you will be on a clear liquid diet.
  • On the night before the test, your doctor may have you take a prescription laxative tablet or drink a laxative solution. This will make you use the bathroom often.

Virtual colonoscopy is still being studied to see if it works as well as a regular colonoscopy. If polyps are found, you will need a regular colonoscopy to have them removed.

What do numbers tell us about the benefits and risks of colon cancer screening tests?

Examples of colon cancer screening benefits and risks for people age 50 to 74*
Screening test People who avoid cancer deaths over their lifetime compared to those who don't have screening Risk of serious complications from the test, including death
Stool test every year 10 out of 1,000 No risk
Sigmoidoscopy every 5 years 10 to 20 out of 1,000 Less than 1 out of 1,000
Colonoscopy every 10 years 30 to 40 out of 1,000 2 to 3 out of 1,000

*Based on the best available evidence (evidence quality: moderate)

Benefits

Colon cancer screening can help reduce cancer deaths. The quality of this evidence is moderate.

Take a group of 1,000 people ages 50 to 74.

  • With a stool test every year, 10 people out of 1,000 will avoid death from cancer over their lifetimes, compared with people who do not have any screening.
  • With a sigmoidoscopy every 5 years, 10 to 20 people out of 1,000 will avoid death from cancer over their lifetimes, compared with people who do not have any screening.
  • With a colonoscopy every 10 years, 30 to 40 people out of 1,000 may avoid death from cancer over their lifetimes, compared with people who do not have any screening.
Risks

There is no risk involved in having a stool test.

Problems are rare with sigmoidoscopy. They are also rare with colonoscopy, but they happen more often with colonoscopy than with sigmoidoscopy. The quality of this evidence is moderate.

Take a group of 1,000 people.

  • If all of them have a sigmoidoscopy, less than 1 person out of 1,000 will have a serious complication from the test, which could include death. This means that more than 999 out of 1,000 people will not have a serious problem.
  • If each one has a colonoscopy, 2 to 3 people out of 1,000 will have a serious complication, which could include death. This means that 997 or 998 people out of 1,000 will not have a serious problem.
Understanding the evidence

Some evidence is better than other evidence. Evidence comes from studies that look at how well treatments and tests work and how safe they are. For many reasons, some studies are more reliable than others. The better the evidence is—the higher its quality—the more we can trust it.

The information shown here is based on the best available evidence.1, 2, 3, 4, 5, 6, 7 The evidence is rated using four quality levels: high, moderate, borderline, and inconclusive.

Another thing to understand is that the evidence can't predict what's going to happen in your case. When evidence tells us that 2 out of 100 people who have a certain test or treatment may have a certain result and that 98 out of 100 may not, there's no way to know if you will be one of the 2 or one of the 98.

What do experts recommend?

Colorectal cancer screening guidelines for people 50 and older at average risk
Test Frequency

Stool test,* such as the fecal occult blood test (FOBT), fecal immunochemical test (FIT), or stool DNA test (sDNA)

Every year for FOBT and FIT

Every 5 years for sDNA

 or

Sigmoidoscopy*

Every 5 years

 or

Colonoscopy

Every 10 years

 or

 

Computed tomographic colonography (CTC), also called a virtual colonoscopy

Every 5 years

*Others recommend combining a stool test with a sigmoidoscopy.

Recommendations from the U.S. Preventive Services Task Force

  • People ages 50 to 75 should have a fecal occult blood test (FOBT), sigmoidoscopy, or colonoscopy.
  • People who have a sigmoidoscopy every 5 years should also have a stool test (FOBT) at regular intervals.
  • Some people older than 75 may benefit from screening tests. Others may not. Talk to your doctor about continuing testing for colon cancer after age 75.

Recommendations from other groups

  • The American Cancer Society (ACS), the American Gastroenterological Association (AGA), and the American College of Gastroenterologists (ACG) recommend routine testing for people age 50 and older who have a normal risk for colon cancer. Your doctor may recommend earlier or more frequent testing if you have a higher risk for colon cancer. Talk to your doctor about when you should be tested.

Compare your options

Compare

What is usually involved?









What are the benefits?









What are the risks and side effects?









Stool testStool test
  • It's done at home.
  • You take samples of your stools and mail them to a lab.
  • It's easy to do at home.
  • It's cheaper than other tests.
  • You don't need to use laxatives or enemas.
  • A "positive" result means other tests will be needed.
Flexible sigmoidoscopyFlexible sigmoidoscopy
  • It's done in a doctor's office, clinic, or hospital.
  • It takes 5 to 15 minutes, or slightly longer if polyps are removed.
  • You don't have to do it as often as a stool test.
  • It can find polyps before they turn into cancer.
  • Polyps can often be removed during the test.
  • It has fewer risks than colonoscopy.
  • This test only sees the lower part of colon.
  • Rare problems include bleeding problems and piercing the colon (perforation).
ColonoscopyColonoscopy
  • It's done in a doctor's office, clinic, or hospital.
  • You use laxatives to clean out your bowels.
  • It takes 30 to 45 minutes, or slightly longer if polyps are removed.
  • You are given drugs to relax. You may not remember the test at all.
  • You don't have to do it as often as other tests.
  • It can find polyps before they turn into cancer.
  • Polyps usually can be removed during the test.
  • This test looks at your entire colon.
  • It costs more than other tests.
  • Bleeding problems and piercing the colon are rare but are more common than with sigmoidoscopy.

Personal stories

Are you interested in what others decided to do? Many people have faced this decision. These personal stories may help you decide.

Personal stories about test methods for colon cancer

These stories are based on information gathered from health professionals and consumers. They may be helpful as you make important health decisions.

My grandmother died of colon cancer, so I think I am going to have a colonoscopy. I know that colonoscopy may have slightly greater risks of complications than a sigmoidoscopy. But I would rather have a colonoscopy to make sure I don't have cancer.

Edna, age 55

I've had a fecal occult blood test every year, and now I'm going to have a sigmoidoscopy. I am a little worried and embarrassed about having a sigmoidoscopy, but I would rather be a little embarrassed than have colon cancer.

Jose Luis, age 54

If I have to have an uncomfortable, embarrassing test, I would rather have one every 10 years than have one every 5 years. Besides, a colonoscopy examines the entire colon, not just part of it.

Frank, age 52

A sigmoidoscopy is a good way for my doctor to look for signs of cancer. I know it can't be used to look at the whole colon, but I feel comfortable that it will detect any problems. And there are fewer risks than with colonoscopy.

Stella, age 58

No one in my family has ever had colon cancer. I try to eat a balanced diet and get plenty of exercise. I am going to do yearly fecal occult blood tests. I am more comfortable doing that than having other more costly procedures. And there are fewer risks.

Patrick, age 56

Cancer seems to run in our family, and a gene test showed that my sister has Lynch syndrome. Her doctor said everyone in my family needs extra screening. As it turns out, I'm having my first colonoscopy next week.

Joycelyn, age 41

What matters most to you?

Your personal feelings are just as important as the medical facts. Think about what matters most to you in this decision, and show how you feel about the following statements.

I'm afraid of a test that involves putting anything into my colon.

Not important
Somewhat important
Very important

I want to have a test that is going to see as much as possible.

Not important
Somewhat important
Very important

It's important to me to do testing at home, in private.

Not important
Somewhat important
Very important

I don't like the idea of having to clean out my bowels before the test.

Not important
Somewhat important
Very important

I don't want to miss any work for this test.

Not important
Somewhat important
Very important

I don't want to have two tests. I want my doctor to remove any polyps right away.

Not important
Somewhat important
Very important

I'm worried about the cost of the tests.

Not important
Somewhat important
Very important

My other important reasons:

Not important
Somewhat important
Very important

Where are you leaning now?

Now that you've thought about the facts and your feelings, you may have a general idea of where you stand on this decision. Show which way you are leaning right now.

Using stool test

NOT using stool test

Leaning toward
Undecided
Leaning toward

Using sigmoidoscopy

NOT using sigmoidoscopy

Leaning toward
Undecided
Leaning toward

Using colonoscopy

NOT using colonoscopy

Leaning toward
Undecided
Leaning toward

What else do you need to make your decision?

Check the facts

1.

Will having regular screening tests lower your chances of dying from colon cancer?

  • YesThat's right. When colon cancer is found early through screening tests, it is more easily treated.
  • NoSorry, that's not right. When colon cancer is found early through screening tests, it is more easily treated.
  • I'm not sureIt may help to go back and read "Get the Facts." When colon cancer is found early through screening tests, it is more easily treated.
2.

Should all adults have regular colon cancer screening?

  • YesSorry, but that's not right. Most people don't need to start regular screening until age 50. You may need to start sooner if you have certain health problems or a family history of colon cancer.
  • NoYou're right. Most people don't need to start regular screening until age 50. You may need to start sooner if you have certain health problems or a family history of colon cancer.
  • I'm not sureIt may help to go back and read "Get the Facts." Most people don't need to start regular screening until age 50. You may need to start sooner if you have certain health problems or a family history of colon cancer.

Decide what's next

1.

Do you understand the options available to you?

2.

Are you clear about which benefits and side effects matter most to you?

3.

Do you have enough support and advice from others to make a choice?

Certainty

1.

How sure do you feel right now about your decision?

Not sure at all
Somewhat sure
Very sure
3.

Use the following space to list questions, concerns, and next steps.

Your Summary

Here's a record of your answers. You can use it to talk with your doctor or loved ones about your decision.

Your decision 

Next steps

Which way you're leaning

How sure you are

Your comments

Your knowledge of the facts 

Key concepts that you understood

Key concepts that may need review

Getting ready to act 

Patient choices

Credits and References

Credits
Author Healthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Specialist Medical Reviewer Kenneth Bark, MD - Surgery,

References
Citations
  1. Hewitson P, et al. (2007). Screening for colorectal cancer using the faecal occult blood test, Hemoccult. Cochrane Database of Systematic Reviews (1).
  2. Ko CW, et al. (2005). Comparing risks and benefits of colorectal cancer screening in elderly patients. Gastroenterology, 239(4): 1163–1170.
  3. Nelson DB, et al. (2002). Procedural success and complications of large-scale screening colonoscopy. Gastrointestinal Endoscopy, 55(3): 307–314.
  4. Walter LC, Covinsky KE (2001). Cancer screening in elderly patients: A framework for individualized decision making. JAMA, 285(21): 2750–2756.
  5. Whitlock EP, et al. (2008). Screening for Colorectal Cancer: An Updated Systematic Review (Evidence Syntheses, No. 65.1). Rockville, MD: Agency for Healthcare Research and Quality. Also available online: http://www.ncbi.nlm.nih.gov/books/NBK35179.
  6. Whitlock EP, et al. (2008). Screening for colorectal cancer: A targeted, updated systematic review for the U.S. Preventive Services Task Force. Annals of Internal Medicine, 149(9): 638–658.
  7. U.S. Preventive Services Task Force (2008). Screening for colorectal cancer: U.S. Preventive Services Task Force recommendation statement. Available online: http://www.uspreventiveservicestaskforce.org/uspstf/uspscolo.htm.
You may want to have a say in this decision, or you may simply want to follow your doctor's recommendation. Either way, this information will help you understand what your choices are so that you can talk to your doctor about them.

Colon Cancer: Which Screening Test Should I Have?

Here's a record of your answers. You can use it to talk with your doctor or loved ones about your decision.
  1. Get the facts
  2. Compare your options
  3. What matters most to you?
  4. Where are you leaning now?
  5. What else do you need to make your decision?

1. Get the Facts

Your options

  • Get a stool test, such as a fecal occult blood test (FOBT), every year.
  • Get a sigmoidoscopy every 5 years.
  • Get a colonoscopy every 10 years.

Key points to remember

  • Screening tests find health problems early, before symptoms appear. Regular testing to find colon cancer early is very important because as soon as there are symptoms, it's usually too late to cure colon cancer.
  • Regular testing lowers your risk of dying from colon cancer.
  • The two main types of tests are:
    • Those that mostly find signs of colon cancer (stool tests).
    • Those that can also help prevent colon cancer by finding polyps before they turn into cancer (sigmoidoscopy and colonoscopy). And if you have a sigmoidoscopy or colonoscopy, any polyps that are found usually can be removed during the test.
  • Routine testing is recommended for everyone age 50 and older who has a normal risk for colon cancer. Your doctor may recommend earlier or more frequent testing if you have a higher risk for colon cancer.
FAQs

What is colorectal cancer?

Colorectal cancer happens when cells that are not normal grow in your colon or rectum . Most people just call it "colon cancer."

These cancers usually begin as polyps, which are growths attached to the inside of the colon or rectum. Colon polyps are common, and most of them do not turn into cancer. Polyps are found during some screening tests. And polyps found during a colonoscopy or sigmoidoscopy usually can be removed at the same time.

Why is regular screening important?

When colon cancer is found early through screening tests, it is more easily treated.

Screening tests can detect or prevent this cancer, but only about half of people older than 50 are screened. According to the American Cancer Society, if everyone were tested, tens of thousands of lives could be saved each year.

Why is your family history important?

A family history of colon cancer makes you more likely to get it. You will need to be screened at an earlier age—and have more frequent screening—than other people if:

  • You have a close relative with colon cancer. You are more likely to get colon cancer if:
    • One of your parents, brothers, sisters, or children had it before the age of 60.
    • Two or more of your parents, brothers, sisters, or children has had it at any age.
  • You have a family history of certain colon problems, such as familial adenomatous polyposis (FAP) or hereditary nonpolyposis colon cancer (HNPCC). Most people who inherit these conditions will get colon cancer if they are not screened and treated.

What are stool tests?

Stool tests involve sending some of your stool to a lab for testing to see if there is evidence of cancer. They don't help prevent colon cancer, but they do help find it early, when it is more treatable.

Stool tests need to be done once a year to find colon cancer as early as possible. These tests can usually be done in the privacy of your home.

There are three types of stool tests:

  • Fecal occult blood test (FOBT). This is the most common stool test. You put tiny samples of your stool on a special card or cloth and send it to a lab. The lab uses certain chemicals to find blood that you can't see with the naked eye. FOBT tests don't cost much.
  • Fecal immunochemical test (FIT). This is a newer test that is a little easier to do at home. It costs more than an FOBT.
  • Stool DNA test (sDNA). This is the newest stool test. It looks for changes in DNA (genetic material) in the stool. It costs the most.

If you can't or won't go to the doctor to get an at-home stool test, you can check your local drugstore for an over-the-counter brand. But you may feel better if you talk to your doctor about what the test results mean.

Risks of stool tests

There is no risk involved in the actual use of a stool test. But there are some things you need to think about:

  • Blood in the stool can be a sign of colon cancer, but it's more often caused by something else, such as hemorrhoids, ulcers, or taking aspirin. These other conditions can cause a "positive" result even when you don't have cancer.
  • If your test is positive, you will probably need to have a colonoscopy.
  • Unlike other tests, stool tests don't help prevent cancer by finding colon polyps before they turn into cancer. Stool tests mostly find cancer that is already present.

What is flexible sigmoidoscopy?

Flexible sigmoidoscopy (say "sig-moy-DAW-skuh-pee") is a test that lets your doctor look at the inside of the lower part of your colon. The doctor looks through a lighted tube that can bend around the corners of the colon.

With this test, the doctor can find polyps in the lower part of your colon and may be able to remove them. Polyps are growths inside the colon that can turn into colon cancer.

When used to screen for colon cancer, this test is usually done every 5 years.

Getting ready for a sigmoidoscopy involves cleaning out the colon:

  • For 1 to 2 days before the test, you may be on a clear liquid diet.
  • You will likely have an enema before the test.

This test usually takes 5 to 15 minutes or slightly longer if polyps are found and removed.

Risks of sigmoidoscopy

There is very little risk of problems from having a sigmoidoscopy.

  • There is a slight chance of piercing the colon (perforation) or causing severe bleeding by damaging the wall of the colon. But this is rare.
  • There is also a slight chance of a colon infection (very rare).

A sigmoidoscopy only looks at the lower part of your colon, which is where most polyps grow. But sometimes polyps grow in the upper part of your colon, and they would not be seen with this test.

If your doctor finds polyps during a sigmoidoscopy, you may need to have a colonoscopy to see if there are more polyps farther up in your colon.

What is colonoscopy?

Colonoscopy (say "koh-luh-NAW-skuh-pee") is a test that lets your doctor look at the inside of your entire colon . The doctor looks through a lighted tube that can bend around the corners of the colon.

With this test, the doctor can find and remove polyps, which are growths inside the colon that can turn into colon cancer.

When used as a screening test for colon cancer, this test is usually done every 10 years. If you have a colonoscopy, you won't need to have a yearly stool test. A colonoscopy may be done more often if your risk is higher than average.

Getting ready for a colonoscopy involves a very thorough cleansing of the colon, which must be completely empty:

  • For 1 to 2 days before the test, you will be on a clear liquid diet.
  • On the night before the test, your doctor may have you take a prescription laxative tablet or drink a laxative solution. This will make you use the bathroom often.

You may be given medicine to help you relax. Many people don't even remember the test afterward because they are so relaxed.

The test usually takes 30 to 45 minutes, but it may take longer if polyps are found and removed.

Risks of colonoscopy

The scope or a small tool may tear the lining of the colon or cause bleeding. Although these problems are rare, they happen more often with colonoscopy than with sigmoidoscopy.

Virtual colonoscopy

A virtual colonoscopy uses pictures taken during a CT scan to look at the colon. With this procedure, a thin tube is inserted into the rectum and air is pumped through the tube into the colon. The air expands your colon so that it is easier to see on an X-ray. If you are interested in learning more about virtual colonoscopy, talk to your doctor.

Getting ready for a virtual colonoscopy involves the same thorough cleansing of the colon that is needed for a regular colonoscopy:

  • For 1 to 2 days before the test, you will be on a clear liquid diet.
  • On the night before the test, your doctor may have you take a prescription laxative tablet or drink a laxative solution. This will make you use the bathroom often.

Virtual colonoscopy is still being studied to see if it works as well as a regular colonoscopy. If polyps are found, you will need a regular colonoscopy to have them removed.

What do numbers tell us about the benefits and risks of colon cancer screening tests?

Examples of colon cancer screening benefits and risks for people age 50 to 74*
Screening test People who avoid cancer deaths over their lifetime compared to those who don't have screening Risk of serious complications from the test, including death
Stool test every year 10 out of 1,000 No risk
Sigmoidoscopy every 5 years 10 to 20 out of 1,000 Less than 1 out of 1,000
Colonoscopy every 10 years 30 to 40 out of 1,000 2 to 3 out of 1,000

*Based on the best available evidence (evidence quality: moderate)

Benefits

Colon cancer screening can help reduce cancer deaths. The quality of this evidence is moderate.

Take a group of 1,000 people ages 50 to 74.

  • With a stool test every year, 10 people out of 1,000 will avoid death from cancer over their lifetimes, compared with people who do not have any screening.
  • With a sigmoidoscopy every 5 years, 10 to 20 people out of 1,000 will avoid death from cancer over their lifetimes, compared with people who do not have any screening.
  • With a colonoscopy every 10 years, 30 to 40 people out of 1,000 may avoid death from cancer over their lifetimes, compared with people who do not have any screening.
Risks

There is no risk involved in having a stool test.

Problems are rare with sigmoidoscopy. They are also rare with colonoscopy, but they happen more often with colonoscopy than with sigmoidoscopy. The quality of this evidence is moderate.

Take a group of 1,000 people .

  • If all of them have a sigmoidoscopy, less than 1 person out of 1,000 will have a serious complication from the test, which could include death. This means that more than 999 out of 1,000 people will not have a serious problem.
  • If each one has a colonoscopy, 2 to 3 people out of 1,000 will have a serious complication, which could include death. This means that 997 or 998 people out of 1,000 will not have a serious problem.
Understanding the evidence

Some evidence is better than other evidence. Evidence comes from studies that look at how well treatments and tests work and how safe they are. For many reasons, some studies are more reliable than others. The better the evidence is—the higher its quality—the more we can trust it.

The information shown here is based on the best available evidence.1, 2, 3, 4, 5, 6, 7 The evidence is rated using four quality levels: high, moderate, borderline, and inconclusive.

Another thing to understand is that the evidence can't predict what's going to happen in your case. When evidence tells us that 2 out of 100 people who have a certain test or treatment may have a certain result and that 98 out of 100 may not, there's no way to know if you will be one of the 2 or one of the 98.

What do experts recommend?

Colorectal cancer screening guidelines for people 50 and older at average risk
Test Frequency

Stool test,* such as the fecal occult blood test (FOBT), fecal immunochemical test (FIT), or stool DNA test (sDNA)

Every year for FOBT and FIT

Every 5 years for sDNA

 or

Sigmoidoscopy*

Every 5 years

 or

Colonoscopy

Every 10 years

 or

 

Computed tomographic colonography (CTC), also called a virtual colonoscopy

Every 5 years

*Others recommend combining a stool test with a sigmoidoscopy.

Recommendations from the U.S. Preventive Services Task Force

  • People ages 50 to 75 should have a fecal occult blood test (FOBT), sigmoidoscopy, or colonoscopy.
  • People who have a sigmoidoscopy every 5 years should also have a stool test (FOBT) at regular intervals.
  • Some people older than 75 may benefit from screening tests. Others may not. Talk to your doctor about continuing testing for colon cancer after age 75.

Recommendations from other groups

  • The American Cancer Society (ACS), the American Gastroenterological Association (AGA), and the American College of Gastroenterologists (ACG) recommend routine testing for people age 50 and older who have a normal risk for colon cancer. Your doctor may recommend earlier or more frequent testing if you have a higher risk for colon cancer. Talk to your doctor about when you should be tested.

2. Compare your options

  Stool test Flexible sigmoidoscopy
What is usually involved?
  • It's done at home.
  • You take samples of your stools and mail them to a lab.
  • It's done in a doctor's office, clinic, or hospital.
  • It takes 5 to 15 minutes, or slightly longer if polyps are removed.
What are the benefits?
  • It's easy to do at home.
  • It's cheaper than other tests.
  • You don't need to use laxatives or enemas.
  • You don't have to do it as often as a stool test.
  • It can find polyps before they turn into cancer.
  • Polyps can often be removed during the test.
  • It has fewer risks than colonoscopy.
What are the risks and side effects?
  • A "positive" result means other tests will be needed.
  • This test only sees the lower part of colon.
  • Rare problems include bleeding problems and piercing the colon (perforation).
  Colonoscopy
What is usually involved?
  • It's done in a doctor's office, clinic, or hospital.
  • You use laxatives to clean out your bowels.
  • It takes 30 to 45 minutes, or slightly longer if polyps are removed.
  • You are given drugs to relax. You may not remember the test at all.
What are the benefits?
  • You don't have to do it as often as other tests.
  • It can find polyps before they turn into cancer.
  • Polyps usually can be removed during the test.
  • This test looks at your entire colon.
What are the risks and side effects?
  • It costs more than other tests.
  • Bleeding problems and piercing the colon are rare but are more common than with sigmoidoscopy.

Personal stories

Are you interested in what others decided to do? Many people have faced this decision. These personal stories may help you decide.

Personal stories about test methods for colon cancer

These stories are based on information gathered from health professionals and consumers. They may be helpful as you make important health decisions.

"My grandmother died of colon cancer, so I think I am going to have a colonoscopy. I know that colonoscopy may have slightly greater risks of complications than a sigmoidoscopy. But I would rather have a colonoscopy to make sure I don't have cancer."

— Edna, age 55

"I've had a fecal occult blood test every year, and now I'm going to have a sigmoidoscopy. I am a little worried and embarrassed about having a sigmoidoscopy, but I would rather be a little embarrassed than have colon cancer."

— Jose Luis, age 54

"If I have to have an uncomfortable, embarrassing test, I would rather have one every 10 years than have one every 5 years. Besides, a colonoscopy examines the entire colon, not just part of it."

— Frank, age 52

"A sigmoidoscopy is a good way for my doctor to look for signs of cancer. I know it can't be used to look at the whole colon, but I feel comfortable that it will detect any problems. And there are fewer risks than with colonoscopy."

— Stella, age 58

"No one in my family has ever had colon cancer. I try to eat a balanced diet and get plenty of exercise. I am going to do yearly fecal occult blood tests. I am more comfortable doing that than having other more costly procedures. And there are fewer risks."

— Patrick, age 56

"Cancer seems to run in our family, and a gene test showed that my sister has Lynch syndrome. Her doctor said everyone in my family needs extra screening. As it turns out, I'm having my first colonoscopy next week."

— Joycelyn, age 41

3. What matters most to you?

Your personal feelings are just as important as the medical facts. Think about what matters most to you in this decision, and show how you feel about the following statements.

I'm afraid of a test that involves putting anything into my colon.

         
Not important
Somewhat important
Very important

I want to have a test that is going to see as much as possible.

         
Not important
Somewhat important
Very important

It's important to me to do testing at home, in private.

         
Not important
Somewhat important
Very important

I don't like the idea of having to clean out my bowels before the test.

         
Not important
Somewhat important
Very important

I don't want to miss any work for this test.

         
Not important
Somewhat important
Very important

I don't want to have two tests. I want my doctor to remove any polyps right away.

         
Not important
Somewhat important
Very important

I'm worried about the cost of the tests.

         
Not important
Somewhat important
Very important

My other important reasons:

 
         
Not important
Somewhat important
Very important

4. Where are you leaning now?

Now that you've thought about the facts and your feelings, you may have a general idea of where you stand on this decision. Show which way you are leaning right now.

Using stool test

NOT using stool test

             
Leaning toward
Undecided
Leaning toward

Using sigmoidoscopy

NOT using sigmoidoscopy

             
Leaning toward
Undecided
Leaning toward

Using colonoscopy

NOT using colonoscopy

             
Leaning toward
Undecided
Leaning toward

5. What else do you need to make your decision?

Check the facts

1. Will having regular screening tests lower your chances of dying from colon cancer?

  • Yes
  • No
  • I'm not sure
That's right. When colon cancer is found early through screening tests, it is more easily treated.

2. Should all adults have regular colon cancer screening?

  • Yes
  • No
  • I'm not sure
You're right. Most people don't need to start regular screening until age 50. You may need to start sooner if you have certain health problems or a family history of colon cancer.

Decide what's next

1. Do you understand the options available to you?

2. Are you clear about which benefits and side effects matter most to you?

3. Do you have enough support and advice from others to make a choice?

Certainty

1. How sure do you feel right now about your decision?

         
Not sure at all
Somewhat sure
Very sure

2. Check what you need to do before you make this decision.

  • I'm ready to take action.
  • I want to discuss the options with others.
  • I want to learn more about my options.

3. Use the following space to list questions, concerns, and next steps.

 
Credits
By Healthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Specialist Medical Reviewer Kenneth Bark, MD - Surgery,

References
Citations
  1. Hewitson P, et al. (2007). Screening for colorectal cancer using the faecal occult blood test, Hemoccult. Cochrane Database of Systematic Reviews (1).
  2. Ko CW, et al. (2005). Comparing risks and benefits of colorectal cancer screening in elderly patients. Gastroenterology, 239(4): 1163–1170.
  3. Nelson DB, et al. (2002). Procedural success and complications of large-scale screening colonoscopy. Gastrointestinal Endoscopy, 55(3): 307–314.
  4. Walter LC, Covinsky KE (2001). Cancer screening in elderly patients: A framework for individualized decision making. JAMA, 285(21): 2750–2756.
  5. Whitlock EP, et al. (2008). Screening for Colorectal Cancer: An Updated Systematic Review (Evidence Syntheses, No. 65.1). Rockville, MD: Agency for Healthcare Research and Quality. Also available online: http://www.ncbi.nlm.nih.gov/books/NBK35179.
  6. Whitlock EP, et al. (2008). Screening for colorectal cancer: A targeted, updated systematic review for the U.S. Preventive Services Task Force. Annals of Internal Medicine, 149(9): 638–658.
  7. U.S. Preventive Services Task Force (2008). Screening for colorectal cancer: U.S. Preventive Services Task Force recommendation statement. Available online: http://www.uspreventiveservicestaskforce.org/uspstf/uspscolo.htm.

Note: The "printer friendly" document will not contain all the information available in the online document some Information (e.g. cross-references to other topics, definitions or medical illustrations) is only available in the online version.

Current as of: August 27, 2012

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.

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