Colorectal Cancer Screening Guidelines

Introduction to Colorectal Cancer Screening

Colorectal cancer screening is crucial for reducing the incidence and mortality of colorectal cancer, with various screening methods available, including colonoscopy, fecal occult blood tests (FOBT), and multitarget stool DNA testing (Cologuard), as recommended by the American Cancer Society and supported by the American College of Physicians 1, 2, 3

Colonoscopy reduces colorectal cancer incidence by more than 50% when polyps are removed, as recommended by the National Comprehensive Cancer Network 4
Colonoscopy allows for the examination of the entire large bowel, enables removal of polyps in the same session, and provides definitive diagnosis through biopsy, making it a crucial step in colorectal cancer screening, as recommended by the American College of Gastroenterology and supported by the American Gastroenterological Association 4

Fecal occult blood testing can reduce colorectal cancer mortality by 15-33% when properly implemented, as stated by the American Cancer Society and supported by the American College of Physicians 2
Guaiac-based tests (gFOBT) have lower sensitivity (37-79% for cancer) and higher specificity (86-98%), and are affected by diet and medications, according to the American College of Physicians 2
Immunochemical tests (FIT) have higher sensitivity (73.8% for cancer) and better specificity (94.9%), and are not affected by diet, as recommended by the American College of Physicians 2
Single in-office testing has extremely low sensitivity (only 4.9% for advanced neoplasia) and should never be used for screening, as recommended by the American Academy of Family Physicians 2

Cologuard combines quantitative molecular assays for KRAS mutations, detection of aberrant NDRG4 and BMP3 methylation, ACTB (β-actin) measurement, and hemoglobin immunoassay, with a sensitivity of 92.3% for colorectal cancer and 42.4% for advanced precancerous lesions, and a specificity of 86.6%, as reported by the NCCN guidelines 5, 4
Comparison of Cologuard to traditional fecal occult blood tests (FIT) shows:
Test Sensitivity for Colorectal Cancer Sensitivity for Advanced Precancerous Lesions Specificity
Cologuard 92.3% 42.4% 86.6%
FIT 73.8% 23.8% 94.9%

Test	Sensitivity for Colorectal Cancer	Sensitivity for Advanced Precancerous Lesions	Specificity
Cologuard	92.3%	42.4%	86.6%
FIT	73.8%	23.8%	94.9%

All positive tests must be followed by colonoscopy within 3-6 months, and delaying colonoscopy beyond 6 months increases the risk of colorectal cancer, as recommended by the American College of Gastroenterology and American Gastroenterological Association 2
A positive Cologuard result should be followed by diagnostic colonoscopy within 3 months, but no later than 6 months, as recommended by the American College of Radiology, American Gastroenterological Association, and U.S. Multi-Society Task Force on Colorectal Cancer 2, 6, 4
Delaying colonoscopy beyond 6 months significantly increases the risk of colorectal cancer (58% higher odds) and advanced-stage disease (116% higher odds), as reported by the American College of Gastroenterology and supported by the American Cancer Society 7

Common barriers to follow-up colonoscopy include lack of understanding, fear, and logistical challenges, which can be addressed through clear communication, education, and assistance, as recommended by the American College of Gastroenterology and American Cancer Society 2, 6
Patient-related factors, such as lack of understanding about the importance of follow-up, fear or anxiety about the colonoscopy procedure, and declining the procedure, account for 49.3% of cases, while provider-related factors account for 16.4% and system-related factors account for 12.1% of cases, as reported by the American College of Gastroenterology and supported by the American Cancer Society 7

The American Cancer Society (ACS) and the U.S. Preventive Services Task Force (USPSTF) recommend starting colorectal cancer screening at age 45 or 50, with options including multitarget stool DNA testing (Cologuard) every 3 years, annual FIT or high-sensitivity gFOBT, colonoscopy every 10 years, CT colonography every 5 years, and flexible sigmoidoscopy every 5 years 3, 8, 9
A negative test does not guarantee absence of colorectal cancer, and annual testing is required for continued protection, as recommended by the American College of Physicians and supported by the American Cancer Society 1