Colorectal Cancer Screening Tests

Colorectal cancer screening tests are used to detect colorectal cancer or precancerous polyps in the colon or rectum. The goal of these tests is to identify individuals with colorectal cancer at an early stage, when it is more treatable.

Types of Colorectal Cancer Screening Tests

• Fecal Occult Blood Test (FOBT): This test checks for blood in the stool, which can be a sign of colorectal cancer. There are two types of FOBT: guaiac-based and immunochemical.
• Fecal Immunochemical Test (FIT): This test is similar to FOBT but uses antibodies to detect blood in the stool.
• Flexible Sigmoidoscopy: This procedure uses a flexible tube with a camera and light on the end to examine the lower part of the colon and rectum for polyps or cancer.
• Colonoscopy: This procedure uses a longer, flexible tube with a camera and light on the end to examine the entire colon for polyps or cancer. During a colonoscopy, any polyps found can be removed.
• Virtual Colonoscopy (CT Colonography): This test uses computed tomography (CT) scans to produce detailed images of the colon and rectum. It is less invasive than traditional colonoscopy but may not detect all types of polyps.
• Stool DNA Test: This test checks for abnormal DNA in the stool, which can be a sign of colorectal cancer or precancerous polyps.

Recommendations for Colorectal Cancer Screening

The American Cancer Society recommends that adults aged 45 to 75 years old undergo regular colorectal cancer screening. The type and frequency of screening tests may vary depending on individual risk factors and medical history.

• People with an average risk of colorectal cancer should start screening at age 45 and continue until age 75.
• People with a higher risk of colorectal cancer, such as those with a family history or previous diagnosis of colorectal cancer or polyps, may need to start screening earlier and have more frequent tests.

Preparation for Colorectal Cancer Screening Tests

The preparation for colorectal cancer screening tests varies depending on the type of test. For example:

• Fecal occult blood tests (FOBT) and fecal immunochemical tests (FIT) require collecting stool samples at home and sending them to a laboratory for analysis.
• Flexible sigmoidoscopy and colonoscopy require bowel preparation, which typically involves following a special diet, taking laxatives, and avoiding solid foods for a period of time before the test.

Risks and Benefits of Colorectal Cancer Screening Tests

Colorectal cancer screening tests have several benefits, including:

• Detecting colorectal cancer at an early stage, when it is more treatable
• Preventing colorectal cancer by detecting and removing precancerous polyps

However, there are also some risks associated with these tests, including:

• Bleeding or perforation of the colon during colonoscopy or flexible sigmoidoscopy
• False positive results, which can lead to unnecessary follow-up testing and anxiety