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Evidence Summary

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Adults 50 to 75 years of age should be screened for colorectal cancer. Adults 76 to 85 years of age may be screened depending on individual factors.

Lin JS, Piper MA, Perdue LA, et al. Screening for Colorectal Cancer: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force. JAMA. 2016;315:2576-94.

Review and guideline questions

In adults at average risk and without symptoms, what are the benefits and harms of screening tests for colorectal cancer? How good are different tests at detecting colorectal cancer? What are the best recommendations for colorectal cancer screening from the U.S. Preventive Services Task Force?*

Background

Symptoms of colorectal cancer include diarrhea or constipation, blood in your stool, a change in your bowel habits, stomach pain or cramps, and tiredness. If found early, colorectal cancer may be cured; however, it often has no symptoms or signs in its early stages. Screening tests may help find colorectal cancer at an early stage. Some screening tests are done using samples of your stool, and some use imaging of your rectum and colon. For some tests, the doctor puts an endoscope (small camera attached to a flexible tube) into your rectum and moves it through part or all of your colon to look for cancer or small growths (polyps or adenomas) that could develop into cancer.

How the review was done

The studies were published in English up to February 2016 and were rated as fair or good quality.

They included people who were 40 years of age or older, had an average risk of getting colorectal cancer, and did not have symptoms.

Studies assessed screening tests for colorectal cancer including stool tests (fecal occult blood test [FOBT] and fecal immunochemical test [FIT]), endoscope tests for part of your colon (flexible sigmoidoscopy) or all of your colon (colonoscopy), and imaging tests (computed tomographic colonography).

What the researchers found

Compared with no colorectal cancer screening, flexible sigmoidoscopy and FOBTs reduced deaths due to colorectal cancer.

Screening tests varied in their ability to detect colorectal cancer or adenomas. There wasn’t enough information to recommend one test over another.

Endoscope tests have risks for bowel puncture (about 36 punctures in 100,000 colonoscopies and 7 in 100,000 sigmoidoscopies) and major bleeding (about 82 major bleeding events in 100,000 colonoscopies and 18 in 100,000 sigmoidoscopies).

Based on the studies included in the review, the U.S. Preventive Services Task Force recommended that people 50 to 75 years of age should be screened for colorectal cancer.* People 76 to 85 years of age may be screened depending on individual factors; those who haven’t been screened when younger may be more likely to benefit.*

Conclusions

People 50 to 75 years of age should be screened for colorectal cancer. The decision to screen people 76 to 85 years of age should be based on individual factors.

 

*Information from: US Preventive Services Task Force, Bibbins-Domingo K, Grossman DC, et al. Screening for colorectal cancer: US Preventive Services Task Force recommendation statement. JAMA. 2016;315:2564-75.

 

Screening tests for colorectal cancer in people with no symptoms and are at average risk

What are the benefits of screening tests?

Outcomes

Screening tests

Number of studies and people

Effects of screening

Death due to colorectal cancer

Flexible sigmoidoscopy, once or twice over 3 to 5 years, vs no screening

4 RCTs (458,002 people)

About 12 fewer people out of 10 000 died from colorectal cancer over 11 to 12 years of follow-up

 

Guaiac fecal occult blood test (gFOBT) every 2 years vs no screening

5 RCTs (404,396 people†)

Fewer people died from colorectal cancer (relative risk reduction of between 9% and 22% at 11 to 30 years of follow-up)

How good are different tests at detecting‡ cancer or adenomas§?

Outcomes

Screening tests

Number of studies and people

Effects of screening

Detecting colorectal cancer

Fecal immunochemical tests (FITs)||

8 studies (38,718 people)

Correctly found cancer in about 73% to 100% of people who had cancer.

Correctly found no cancer in about 87% to 96% of people who did not have cancer.

Detecting advanced adenomas

FITs||

8 studies (38,718 people)

Correctly found adenomas in about 22% to 44% of people who had them.

Correctly found no adenomas in about 90% to 97% of people who did not have them.

Detecting adenomas 6 mm or larger

Computed tomographic colonography with medication to cleanse the bowel before the test

7 studies (5,328 people)

Correctly found adenomas in about 73% to 98% of people who had them.

Correctly found no adenomas in about 80% to 93% of people who did not have them.

What are the harms of screening tests?

Outcomes

Screening tests

Number of studies and people

Effects of screening

Bowel puncture

Colonoscopy

26 studies (3,414,108 people)

About 36 punctures occurred for every 100,000 colonoscopies done (from as few as 24 to as many as 54 in 100,000 colonoscopies)

 

Flexible sigmoidoscopy

16 studies (329,698 people)

About 7 punctures occurred for every 100,000 sigmoidoscopies done (from as few as 4 to as many as 14 in 100,000 sigmoidoscopies)

Major bleeding

Colonoscopy

22 studies (3,347,101 people)

About 82 major bleeding events occurred for every 100,000 colonoscopies done (from as few as 50 to as many as 135 in 100,000 colonoscopies).

 

Flexible sigmoidoscopy

10 studies (137,987 people)

About 18 major bleeding events occurred for every 100,000 sigmoidoscopies done (from as few as 7 to as many as 44 in 100,000 sigmoidoscopies).

RCT = randomized controlled trial.

†The review author provided this information.

‡Screening tests are compared with a “gold standard” screening test that is very good at detecting cancer or adenomas (usually colonoscopy for colorectal cancer) but that may have some harms. If a newer screening test is good, it will find most cancers detected by the gold standard test and will not find cancer when no cancer was detected by the gold standard test.

§Adenomas are a type of polyp (small growth) found in the colon that can sometimes develop into cancer.

||OC-Light test in 3 studies (25,924 people) and OC FIT-CHEK test in 5 studies (12,794 people).




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