How often do I need a colonoscopy for colorectal cancer screening?

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How often someone needs colorectal cancer screening depends on their risk of developing the disease. People at increased or high risk should undergo screening more regularly than those at average risk.

Screening guidelines

Average-risk individuals need to begin colorectal cancer screening at 45 years of age, with people at higher risk beginning earlier. After someone is 75 years of age, doctors make screening recommendations on a case-by-case basis.

Individuals with typical results on stool-based tests can usually have subsequent tests at the recommended interval, typically every 1–3 years, depending on the specific test.

However, further testing or more frequent screenings may be necessary if doctors find abnormalities during a visual exam or stool-based test.

Learn more about colorectal cancer.

Several screening test options are available for colorectal cancer, including stool-based tests and visual exams of the colon and rectum.

Stool-based tests

There are three standard stool-based tests for colorectal cancer.

• Guaiac-based fecal occult blood test (gFOBT): This test detects small amounts of blood in the stool, which may indicate the presence of polyps or cancer. It is usually an annual test.
• Fecal immunochemical test (FIT): Similar to gFOBT, FIT detects blood in the stool. It is more specific for human blood and does not require dietary restrictions. It is typically an annual test.
• Stool DNA test: This test analyzes the stool sample for genetic changes relating to colorectal cancer. It typically happens every 3 years.

Visual exams of the colon and rectum

The three main visual exams include:

• Colonoscopy: Doctors consider this method the gold standard for colorectal cancer screening. It involves visually examining the entire colon and rectum using a colonoscope, which is a flexible tube with a camera. Doctors usually recommend a colonoscopy every 10 years if no abnormalities are present.
• Flexible sigmoidoscopy: This procedure examines the lower part of the colon using a flexible tube with a camera called a sigmoidoscope. This exam typically happens every 5 years, and doctors may combine this approach with stool-based tests for a more comprehensive screening.
• Virtual colonoscopy (CT colonography): This noninvasive imaging test uses CT scans to create detailed images of the colon. It typically happens every 5 years.

Read about 7 alternatives to colonoscopy.

Individuals at average risk for colorectal cancer do not have any specific risk factors that would place them in a higher-risk category. The following factors constitute an average risk:

• Age: Colorectal cancer risk increases with age, so younger people tend to be at average risk.
• Personal history: Doctors consider individuals with no history of colorectal cancer, precancerous polyps, or inflammatory bowel diseases, such as ulcerative colitis or Crohn’s disease, at average risk.
• Family history: Average-risk individuals do not have a significant family history of colorectal cancer or certain types of polyps. Generally, a significant family history refers to having a biological parent, sibling, or child with colorectal cancer or certain types of precancerous polyps.
• Genetic syndromes: Individuals without known genetic syndromes relating to an increased risk of colorectal cancer, such as Lynch syndrome or familial adenomatous polyposis (FAP), are at average risk.

The following factors may increase people’s risk of developing colorectal cancer:

• Sex: Males are at higher risk than females of developing the disease.
• Race: Black males and females have the highest risk of developing and dying of colorectal cancer compared with non-Hispanic white people. Similarly, American Indian and Alaska Native populations also have an elevated risk of colorectal cancer mortality.

Read about cancer in African American people.

Individuals who have had colorectal cancer or have a history of certain types of precancerous polyps are at high risk for developing new cases of colorectal cancer.

Certain genetic conditions have links to a high risk of colorectal cancer. These include:

• Lynch syndrome, also called hereditary nonpolyposis colorectal cancer: Individuals with Lynch syndrome have a significantly increased risk of developing colorectal cancer and other types of cancer, such as endometrial, ovarian, and stomach cancer.
• Familial adenomatous polyposis (FAP): In FAP, numerous precancerous polyps develop in the colon and rectum, leading to a nearly 100% risk of colorectal cancer without treatment.

Individuals with a strong family history of colorectal cancer or certain types of polyps are at high risk. This includes:

• First-degree relatives: Having a biological parent, sibling, or child with colorectal cancer or certain types of precancerous polyps increases the risk.
• Multiple family members: The risk is higher if multiple family members are affected or if the affected relatives received a diagnosis at a young age.

Specific screening guidelines may apply for high risk individuals to ensure early detection and appropriate management. These guidelines may include:

• Earlier screening: Screening may begin at an earlier age than for average-risk individuals. For example, individuals with a strong family history or hereditary syndromes may start screening in their 20s or 30s.
• More frequent screening: High-risk individuals often require more frequent screening intervals, such as every 1–3 years.

Having regular colorectal cancer screenings is important for catching colorectal cancer early. Some people need screening more regularly than others.

Individuals can talk with a doctor if they think they may have an increased or high risk of developing colorectal cancer.