Colorectal cancer screening can help your doctor find and remove precancerous polyps before they become cancer or find colorectal cancer early when it’s most treatable.
Colorectal cancer screening involves medical tests to check for colorectal cancer when you don’t have any symptoms.
Colorectal cancer is cancer that starts in your colon or rectum, both of which make up your large bowel. It often starts as a polyp (a tissue growth) on the inner lining of your colon or rectum. Most polyps aren’t cancer, but some types can become cancer over time.
Colorectal cancer may not cause noticeable symptoms during the earliest stages when it’s most treatable. That’s why screening is important.
“The benefits of screening are finding polyps before they become cancer and finding cancer at an earlier stage,” Rachel Issaka, MD, MAS, Director of the Population Health Colorectal Cancer Screening Program at the Fred Hutch Cancer Center in Seattle, WA, told Healthline.
“We know that when it’s detected early, colorectal cancer has a high survival rate.
Read on to learn more about colorectal cancer screening, including the potential benefits, what it involves, and risk factors that might affect your need for early or frequent screening.
The American College of Gastroenterology (ACG) published updated guidelines in 2021 that suggest starting screening for colorectal cancer at age 45 years if you have an average risk of developing this cancer.
This represents a change from earlier guidelines, which recommended screening starting at age 45 years for most Black Americans but age 50 for most other adults.
The U.S. Preventive Services Task Force (USPSTF) and the
Your doctor may encourage you to start screening before you’re 45 years old if you have certain risk factors that increase your chances of colorectal cancer, such as:
- a family history of colorectal cancer or advanced polyps
- certain genetic changes that increase your risk of colorectal cancer
- certain medical conditions, such as inflammatory bowel disease or primary sclerosing cholangitis
You can learn more about these risk factors below.
The ACG recommends one-step or two-step testing for colorectal cancer screening.
One-step testing
One-step testing involves a colonoscopy, which is where a doctor examines the inside of your colon or rectum.
The doctor will insert a thin, flexible tube with an attached light and camera into your rectum and the full length of your colon. This instrument is known as a scope.
They use the scope to look for polyps and other signs of tissue changes. They may remove any polyps they find or take tissue samples to check for cancer cells.
Two-step testing
Two-step testing begins with one of the following tests:
- Fecal immunochemical test (FIT): Your doctor, healthcare team, or public health agency gives you a kit to collect a sample of your stool. You return the stool sample to your doctor or clinic or send it directly to a medical laboratory for testing. The lab checks for tiny amounts of blood in the stool that may be a sign of cancer.
- Other stool-based tests: A laboratory may use other stool-based tests, such as the multitarget stool DNA test (mtsDNA), instead of FIT to check for biomarkers of cancer.
- Flexible sigmoidoscopy: A doctor inserts a scope into your rectum and the lower end of your colon to check for signs of cancer.
- CT colonography: An imaging technologist uses a CT scan to create pictures of the inside of your colon, which a doctor examines for signs of cancer.
- Colon capsule endoscopy: You swallow a small capsule with a wireless camera inside to take pictures of the inside of your digestive tract, which a doctor examines for signs of cancer.
If one of these tests is positive for signs of colorectal cancer, your doctor will order a colonoscopy as the second step in two-step testing.
The ACG recommends FIT for two-step testing, but sometimes, your doctor may use one of the other tests above instead.
Although a blood-based screening test is also available for colorectal cancer, the ACG doesn’t recommend it.
Talk with your doctor to learn more about the potential benefits and risks of different types of screening tests.
The 2021 ACG guidelines recommend:
- screening for colorectal cancer with FIT every year
- screening for colorectal cancer with colonoscopy every 10 years
Your doctor may recommend screening more or less frequently if you have certain risk factors for colorectal cancer or you’re using other types of screening tests, such as multitarget stool DNA test or flexible sigmoidoscopy.
Talk with your doctor to learn how often you should get screening.
You can also take the Fight Colorectal Cancer’s screening quiz to assess your individual risk.
At what age should I stop screening?
The 2021 ACG guidelines recommend screening at regular intervals until age 75 years if you have an average risk of colorectal cancer.
The risks of screening after age 75 years might outweigh the benefits for some people. Talk with your doctor to understand the potential benefits and risks. They may encourage you to stop screening at age 75 years or continue screening.
Colorectal cancer is the
Roughly
Overall rates of colorectal cancer diagnoses and deaths have dropped in recent decades, likely due to changes in risk factors, improved screening, and improved treatment. Most of those improvements have been reported among older adults.
“Over the past 3 decades, we’ve seen a relative increase in colon cancer in people who are under the age of 50,” said Dr. Issaka. Colorectal cancer diagnoses in people under the age of 50 years increased by
The following risk factors may increase your chances of colorectal cancer.
Your doctor may recommend earlier or more frequent colorectal cancer screening if you have certain risk factors.
Family history or inherited genetic conditions
You’re more likely to develop colorectal cancer if you’re closely related to someone who’s had this type of cancer or an advanced colorectal polyp, which is a polyp that’s close to becoming cancer.
Let your doctor know if you have any biological relatives who’ve gotten a diagnosis of colorectal cancer or an advanced polyp.
You should also let your doctor know if anyone in your family has had a known genetic condition that increases the risk of colorectal cancer, such as familial adenomatous polyposis (FAP) or hereditary non-polyposis colorectal cancer (Lynch syndrome).
Your doctor will consider how many relatives you have with a history of these conditions, how old they were when they got their diagnoses, and how closely related they are to you.
In some cases, they might recommend one or more of the following:
- starting colorectal cancer screening earlier than usual, at either age 40 years or when you’re 10 years younger than your youngest affected relative was when they got their diagnosis of colorectal cancer or an advanced polyp
- getting colonoscopy screening more often than usual, such as every 5 years
- getting genetic tests to learn whether you have certain genetic conditions
Talk with your doctor to learn more about how your family history or genetic conditions might affect your colorectal cancer risk and screening recommendations.
Inflammatory bowel disease (IBD)
Your risk of colorectal cancer is higher if you have IBD, such as Crohn’s disease or ulcerative colitis.
A 2021 clinical practice review from the American Gastroenterological Association (AGA) recommends starting colonoscopy screening 8 to 10 years after you get a diagnosis of IBD.
It recommends repeating colonoscopy screening every 1 to 5 years after that, depending on how much inflammation IBD is causing and whether you have other risk factors.
Primary sclerosing cholangitis (PSC)
Your risk of colorectal cancer is higher if you have PSC, which is a chronic liver condition that causes inflammation and scarring of your bile ducts.
The 2021 clinical practice review from the AGA recommends getting a colonoscopy as soon as you receive a diagnosis of PSC. It recommends repeating colonoscopy every 1 to 5 years after that depending on your specific risk factors.
Other risk factors
Other risk factors that increase your chances of colorectal cancer
- race or ethnicity
- age 50 years or over
- overweight or obesity
- low physical activity level
- a diet low in fiber, fruits, and vegetables
- a diet high in fat or processed meats
- alcohol consumption
- tobacco use
According to the
Your doctor may recommend lifestyle habits or lifestyle changes to manage some of these risk factors. For example, they may encourage:
- getting more exercise
- eating less saturated fat or processed foods
- eating more fruits, vegetables, whole grains, legumes, or lean proteins
- adjusting the amount of calories that you consume or burn
- taking steps to quit smoking or stop using other tobacco products
- limiting or avoiding alcohol
Let your doctor know if you’re finding it hard to make the recommended changes. They may share tips and resources or refer you to a specialist, such as a registered dietitian or smoking cessation counselor.
It’s never too early to start talking with your doctor about health screenings, Dr. Issaka noted.
“I think about the 18-year-old who’s transitioning from pediatric care to an adult physician. That’s a great time to talk about the screening tests we recommend for you at 20, at 30, at 40, at 50,” Issaka explained.
Your doctor can help you learn when you should start screening for colorectal cancer, as well as other health conditions such as heart disease, diabetes, and other types of cancer.
“I hear from a lot of patients that screening seems like a daunting task, but once it’s broken down into steps, it is very manageable,” Dr. Issaka said.
“As a member of a healthcare team, we are here to support patients through that process, so don’t be shy about asking questions, whether it’s resources that you need to help or information about alternatives,” she continued.
Here are some questions that might be helpful to ask your doctor:
- What are the risk factors for colorectal cancer?
- How can I manage my risk for colorectal cancer?
- When should I start screening for colorectal cancer?
- What type of screening tests do you recommend for me?
- What are the benefits and risks of different types of tests?
- What will the test involve? How can I prepare for it?
- When will the test results be ready?
- Will you contact me to share the results?
- What does it mean if a test is positive?
- When should I repeat the test again?
- Is there someone on your staff who can help me learn how much the recommended tests will cost and whether my health insurance plan will cover them?
Let your doctor know if you don’t understand any of the information they share with you or you have concerns about their recommendations.
“We want patients to have those conversations with us so we can help identify barriers and make sure that get the care that you need,” said Dr. Issaka.
Screening for colorectal cancer may help your doctor find and remove precancerous polyps before they become cancer.
It may also help your doctor diagnose and treat colorectal cancer early on, if it does develop.
Diagnosing and treating colorectal cancer early improves treatment outcomes, including survival rates.
Following your doctor’s recommendations for colorectal cancer screening may lower your chances of developing this cancer and help you get early treatment if it does develop.
Current guidelines suggest starting screening for colorectal cancer at the age of 45 if you have an average risk of developing this type of cancer. Your doctor may recommend starting screening earlier if you have certain risk factors that increase your chances of developing it.
Current guidelines recommend screening at regular intervals after you start.
Your doctor can help you learn how often you should get screening.
They can also help you learn about the various screening tests available, including the potential benefits and risks of different types.
They may advise lifestyle changes as well as colorectal cancer screening to help lower your chances of getting this cancer.
