Colorectal screening checks for signs of cancer in the colon and rectum before symptoms appear. These tests find precancerous growths, called polyps, which can develop into cancer over time. Identifying and removing polyps early can prevent cancer from forming.
Screening also detects colorectal cancer at its earliest stages, when treatment is most effective. This proactive approach reduces the risk of death and complications associated with the disease.
Standard Screening Recommendations
For individuals at average risk, major health organizations like the American Cancer Society (ACS) and the U.S. Preventive Services Task Force (USPSTF) recommend starting colorectal cancer screening at age 45. This recommendation reflects a rising incidence of colorectal cancer in younger adults. Screening continues until age 75 for most individuals.
After age 75, decisions about continuing screening should be made with a healthcare provider, considering individual health status and life expectancy. The frequency of screenings varies by method. For example, a normal colonoscopy is repeated every 10 years.
Other screening methods, such as stool-based tests, have different frequencies. A fecal immunochemical test (FIT) is performed annually. Stool DNA tests, which look for altered DNA and blood, are recommended every one to three years.
The choice of screening method and its frequency should be a shared decision between the patient and their healthcare provider, considering personal preferences and the test’s effectiveness.
Types of Screening Methods
Several methods are available for colorectal cancer screening.
Stool-Based Tests
These tests are non-invasive and performed at home, examining stool samples for markers.
The Fecal Immunochemical Test (FIT) uses antibodies to detect small amounts of blood in the stool, which can indicate polyps or cancer.
The guaiac-based Fecal Occult Blood Test (gFOBT) also checks for hidden blood, using a different chemical reaction.
Stool DNA tests, such as Cologuard, combine the detection of blood with the analysis of altered DNA fragments shed from polyps or tumors into the stool. These tests require collecting an entire bowel movement sample.
Visual Exams
These exams allow healthcare providers to view the colon and rectum.
A colonoscopy involves inserting a long, flexible tube with a camera into the rectum to examine the entire colon. During this procedure, providers can identify and remove polyps, which are then sent for biopsy. This method requires bowel preparation.
A flexible sigmoidoscopy is similar to a colonoscopy but examines only the lower third of the colon and the rectum. This test uses a shorter, flexible tube and may be performed every five years, sometimes with annual stool testing.
CT colonography, also known as virtual colonoscopy, uses X-rays and computed tomography to create detailed images of the colon for a non-invasive assessment.
Screening for Increased Risk
Certain factors elevate an individual’s risk for colorectal cancer, requiring tailored screening guidelines.
Family History
A strong family history of colorectal cancer or advanced polyps in a first-degree relative (parent, sibling, or child) indicates increased risk. In such cases, screening may begin before age 45 and occur more frequently.
Inflammatory Bowel Disease (IBD)
A personal history of inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis, also increases colorectal cancer risk due to chronic inflammation in the colon. These individuals require more intensive surveillance, with frequency and type determined by disease duration and extent. Regular colonoscopies are recommended to monitor for precancerous changes.
Genetic Syndromes
Genetic syndromes raise the risk for colorectal cancer.
Lynch syndrome, a hereditary condition, increases the lifetime risk of developing colorectal cancer and requires screening as early as the 20s, with colonoscopies every one to two years.
Familial Adenomatous Polyposis (FAP) is another genetic condition characterized by numerous polyps, leading to cancer at a young age; screening for FAP starts in early adolescence.
These higher-risk groups benefit from personalized screening plans developed with their healthcare providers. Screening for these groups begins earlier and occurs more frequently to detect and address abnormalities before they progress to advanced cancer.
Interpreting Results and Follow-Up
Understanding screening results and follow-up steps is important for colorectal health. If a stool-based test, such as FIT or a stool DNA test, yields a positive result, it indicates blood or altered DNA, requiring further investigation. A positive stool test does not confirm cancer but indicates the need for a diagnostic colonoscopy.
During a colonoscopy, if polyps are found, they are removed during the procedure. Removed polyps are sent for microscopic examination to determine if they are benign, precancerous, or cancerous. Polyp characteristics (size, number, type) influence future surveillance recommendations.
Following a colonoscopy, the healthcare provider will outline a follow-up schedule based on the findings. If no polyps are found and the colonoscopy is normal, a repeat screening is recommended in 10 years for average-risk individuals. However, if polyps are removed or other abnormalities are noted, a shorter surveillance interval, such as every three to five years, may be advised.
Adhering to follow-up recommendations is important for ongoing monitoring and early detection of new polyps or cancerous changes. Regular communication with a healthcare provider ensures an appropriate plan based on individual results and risk factors.