Question 1

At what age should you get your first colonoscopy?

Accepted Answer

Colorectal cancer screening starts at 45 for adults at average risk. A colonoscopy is one of several recommended tests; a yearly stool test is another. The USPSTF lowered the starting age from 50 to 45 in 2021.

Question 2

How often do you need a colonoscopy?

Accepted Answer

Every 10 years, in the USPSTF list of screening intervals for adults at average risk. Other tests have shorter intervals: FIT or high-sensitivity gFOBT every year, stool DNA-FIT every 1 to 3 years, CT colonography or flexible sigmoidoscopy every 5 years.

Question 3

At what age can you stop colon cancer screening?

Accepted Answer

The grade A range ends at 75. From 76 to 85 the USPSTF advises screening selectively, weighing overall health, past screening and preferences; adults who have never been screened are more likely to benefit. For adults 86 or older it says evidence is lacking and other health problems likely outweigh any benefit.

Question 4

Which colorectal screening test is best?

Accepted Answer

The USPSTF does not name one. It says "the risks and benefits of different screening tests vary": they differ in how often you repeat them, whether they are done at home or in an office, bowel preparation, sedation, and what happens after an abnormal result. Talking these through can help pick a test you are more likely to complete.

Question 5

Cologuard vs colonoscopy: what is the difference?

Accepted Answer

Cologuard is a stool DNA test (also called a FIT-DNA test) that you collect at home from a kit your provider orders. The USPSTF calls this test sDNA-FIT and lists it every 1 to 3 years; colonoscopy is every 10 years. An abnormal stool DNA test needs a follow-up colonoscopy. Both are on the USPSTF list of recommended strategies.

Question 6

FIT or Cologuard: which stool test?

Accepted Answer

In the modeling the USPSTF reviewed, a FIT every year or sDNA-FIT every year gained more life-years than a high-sensitivity gFOBT every year or sDNA-FIT every 3 years. Yearly sDNA-FIT led to more follow-up colonoscopies than yearly FIT. The USPSTF calls sDNA-FIT every 1 to 3 years "a reasonable balance".

Question 7

Colonoscopy, CT colonography or sigmoidoscopy?

Accepted Answer

Colonoscopy and CT colonography can generally see the entire colon; flexible sigmoidoscopy sees only the rectum and the lower part of the colon. In the modeling the USPSTF reviewed, colonoscopy every 10 years or CT colonography every 5 years gained more life-years than flexible sigmoidoscopy every 5 years. CT colonography can also find things outside the colon that need more tests.

Question 8

Should you get a colonoscopy after 75?

Accepted Answer

Not automatically. From 76 to 85 the USPSTF says to decide person by person, and the American Cancer Society says the same. People who have never been screened are the most likely to benefit. After 85, the ACS says to stop.

Question 9

Is a blood test for colon cancer a screening option?

Accepted Answer

The American Cancer Society says blood-based tests are not preferred screening options at this time. They are not on the 2021 USPSTF list of strategies. Ask your doctor before choosing one.

Question 10

What happens if a stool test is positive?

Accepted Answer

You need a colonoscopy to find out why. The USPSTF says follow-up colonoscopy is needed after an abnormal stool test, CT colonography or flexible sigmoidoscopy.

Question 11

Does a family history change when I start?

Accepted Answer

The USPSTF notes higher rates of colorectal cancer in people with a family history, even without a known inherited syndrome, and says all adults 45 or older should be offered screening. A known genetic syndrome is outside this recommendation, so ask your clinician about an earlier or more frequent plan.

Question 12

Does Medicare pay for a colonoscopy?

Accepted Answer

Medicare Part B covers a screening colonoscopy once every 120 months if you are not at high risk (or 48 months after a flexible sigmoidoscopy), and once every 24 months if you are at high risk. You pay nothing for the screening if the provider accepts assignment, including a follow-up colonoscopy after a positive Medicare-covered stool or blood-based test. If a polyp is removed, you pay 15% of the Medicare-approved amount for the doctor, and a 15% facility coinsurance in a hospital outpatient setting or surgery center.

Test	What it looks at	How often	After an abnormal result
High-sensitivity gFOBT or FIT	Blood in the stool (stool sample)	Every year	Colonoscopy if abnormal
Stool DNA-FIT (sDNA-FIT)	DNA markers and blood in the stool (stool sample)	Every 1 to 3 years	Colonoscopy if abnormal
CT colonography	X-ray images, generally the entire colon	Every 5 years	Colonoscopy if abnormal; findings outside the colon may need more tests
Flexible sigmoidoscopy	Camera, rectum and lower colon only	Every 5 years, or every 10 years with a FIT every year	Colonoscopy if abnormal
Colonoscopy	Camera, generally the entire colon	Every 10 years

Age	USPSTF (2021)	American Cancer Society
45 to 49	Screen (grade B)	Start regular screening at 45
50 to 75	Screen (grade A)	Keep screening through 75 if in good health with a life expectancy over 10 years
76 to 85	Decide case by case (grade C): overall health, past screening, preferences	Decide case by case: preferences, life expectancy, overall health, past screening
86 and older	Evidence lacking; other health problems likely outweigh any benefit	No longer screen

Colorectal cancer screening

When it starts, when it can stop

Who it is for

Test and how often

Which test, how often

Screening by age: when to keep going and when to stop

Where the USPSTF draws the line

Questions people ask