How to check for colon cancer
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How to Check for Colon Cancer
Importance of Colorectal Cancer Screening
Colorectal cancer (CRC) is a significant health concern as it is the second leading cause of cancer death in the United States. Early detection through screening is crucial because CRC often does not present symptoms until it is advanced and more difficult to treat. Screening helps identify cancer or precancerous polyps, which can be removed to prevent cancer development.
Recommended Screening Methods for Average-Risk Adults
Stool-Based Tests
Stool-based tests, such as the fecal immunochemical test (FIT) and the guaiac fecal occult blood test (gFOBT), are non-invasive and can be done at home. These tests detect blood in the stool, which can be a sign of polyps or cancer. If blood is found, a follow-up colonoscopy is recommended. However, these tests have a higher rate of false positives, necessitating further invasive testing.
Colonoscopy
Colonoscopy is considered the gold standard for CRC screening. It involves using a flexible tube with a camera to visualize the entire colon and remove any polyps found. This method is highly sensitive and allows for longer intervals between screenings, typically every 10 years for average-risk adults . However, it is invasive, requires bowel preparation, and may involve sedation.
Flexible Sigmoidoscopy
Flexible sigmoidoscopy is similar to colonoscopy but only examines the lower part of the colon. It is less invasive and can be combined with FIT every two years for more comprehensive screening. However, it may miss neoplasms located in the upper colon .
Combined Testing
Combining fecal occult blood testing with sigmoidoscopy can improve detection rates but still misses a significant percentage of advanced neoplasms . Therefore, while useful, it is not as comprehensive as a full colonoscopy.
Emerging Screening Methods
DNA Testing and Molecular Screening
Advances in molecular techniques have led to the development of DNA tests that detect genetic mutations associated with CRC in stool samples. These tests are becoming more accurate and may eventually provide a non-invasive alternative to traditional methods . However, current DNA tests still have limitations in sensitivity and specificity.
MicroRNA (miRNA) Biomarkers
Recent research has identified specific circulating microRNAs (miRNAs) in plasma that can serve as non-invasive biomarkers for CRC detection. A panel of four miRNAs (miR-28-3p, let-7e-5p, miR-106a-5p, and miR-542-5p) has shown promise in distinguishing cancer from non-cancer cases with high accuracy and specificity. This method could potentially offer a simpler and less invasive screening option in the future.
Screening Recommendations
The American College of Physicians (ACP) recommends that average-risk adults aged 50 to 75 years undergo regular CRC screening. The choice of screening method should be based on a discussion between the clinician and the patient, considering the benefits, harms, and costs of each method. Screening should not continue in adults aged 75 years or older or those with a life expectancy of 10 years or less.
Conclusion
Screening for colorectal cancer is essential for early detection and prevention. Various methods, including stool-based tests, colonoscopy, and emerging molecular techniques, offer different benefits and limitations. Clinicians and patients should work together to choose the most appropriate screening strategy based on individual risk factors and preferences.
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