Is CancerGuard a reliable test for colorectal (colon) cancer screening?

CancerGuard is Not a Reliable Colorectal Cancer Screening Test

CancerGuard is not recognized as a reliable colorectal cancer screening test in any major screening guidelines and should not be used for colorectal cancer screening. The American Cancer Society, US Multi-Society Task Force on Colorectal Cancer, American College of Radiology, and US Preventive Services Task Force do not include CancerGuard in their recommended screening options 1.

Recommended Colorectal Cancer Screening Tests

The following screening tests are recognized as reliable options by major guidelines:

• First-tier options (preferred):

  • Colonoscopy every 10 years 2
  • Annual Fecal Immunochemical Test (FIT) 2

• Second-tier options:

  • Cologuard (stool DNA-FIT) every 3 years 2
  • Flexible sigmoidoscopy every 5 years 1
  • CT colonography every 5 years 1
  • Guaiac-based fecal occult blood test (gFOBT) annually 1

Performance Characteristics of Established Tests

Stool-Based Tests

• FIT: Sensitivity for colorectal cancer detection ranges from 73-88% with specificity of 90-96% 1, 3
• Stool DNA-FIT (Cologuard): Higher sensitivity for cancer detection (92.3%) compared to FIT alone, but lower specificity (86.6% vs 94.9%) 2, 1
• gFOBT: Sensitivity for cancer detection ranges from 50-75% with specificity of 96-98% 1

Direct Visualization Tests

• Colonoscopy: Considered the gold standard with sensitivity of 89-95% for detecting adenomas ≥10mm 1, 4
• CT Colonography: Comparable to colonoscopy for detecting adenomas ≥6mm (sensitivity 73-98%, specificity 89-91%) 1
• Flexible Sigmoidoscopy: Associated with reduced colorectal cancer mortality in randomized trials 1, 3

Recent Developments in Blood-Based Testing

A recent study published in the New England Journal of Medicine (2024) evaluated a cell-free DNA blood-based test for colorectal cancer screening, showing:

• 83.1% sensitivity for detecting colorectal cancer
• 89.6% specificity for advanced neoplasia
• Only 13.2% sensitivity for advanced precancerous lesions 5

This demonstrates that even the most recent blood-based tests still have limitations, particularly in detecting precancerous lesions, which is crucial for cancer prevention.

Important Considerations for Screening

• Test selection should prioritize cancer prevention: Tests that can detect both early cancer and adenomatous polyps (like colonoscopy) should be encouraged when resources are available and patients are willing to undergo an invasive test 1

• Program sensitivity vs. test sensitivity: Guidelines emphasize that a screening test must detect the majority of prevalent or incident cancers at the time of testing 1

• Quality matters: Poor-quality testing can miss the majority of prevalent cancers, leading to higher mortality rates 1

Conclusion

For colorectal cancer screening, patients should choose from established, evidence-based options recommended in major guidelines. CancerGuard is not included in these recommendations and should not be used for colorectal cancer screening. Patients should discuss with their healthcare providers which of the recommended screening options is most appropriate based on their individual risk factors, preferences, and access to healthcare resources.