Does Cologuard (multitarget stool DNA test) detect polyps?

Cologuard's Ability to Detect Colorectal Polyps

Yes, Cologuard (multitarget stool DNA test) does detect polyps, but with limited sensitivity for advanced adenomas (42.4%) and even lower sensitivity for non-advanced polyps. 1, 2

Detection Capabilities of Cologuard

• Cologuard combines stool DNA testing with a fecal immunochemical test (FIT) component, detecting methylated BMP3, methylated NDRG4, mutant KRAS, and a marker of total human DNA 1
• The test demonstrates significantly better sensitivity than FIT for detecting:
  • Colorectal cancer (92.3% vs 73.8%, p=0.002) 2
  • Advanced adenomas (42.4% vs 23.8%, p<0.001) 2
  • Polyps with high-grade dysplasia (69.2% vs 46.2%, p=0.004) 2
  • Sessile serrated polyps ≥1 cm (42.4% vs 5.1%, p<0.001) 2

Limitations for Polyp Detection

• The sensitivity for advanced adenomas (42.4%) is considered low, making Cologuard suboptimal for screening precancerous lesions 1
• Specificity is lower than FIT (86.6% vs 94.9%), resulting in more false positives 2
• For non-advanced polyps, the sensitivity is even lower, with 68% of patients having either normal colonoscopy or hyperplastic polyps after a positive Cologuard test 3

Clinical Implications

• Cologuard is FDA-approved for colorectal cancer screening in average-risk adults aged 45-85 years 1
• It is included as an acceptable screening method in the 2016 USPTF screening guidelines and the 2014 American Cancer Society's colorectal cancer prevention guidelines 1
• The positive predictive value for detecting:
  • Colorectal cancer is only 1.3% 3
  • Precancerous lesions plus colorectal cancer is 7.7% 3
• Nearly 90% of individuals with positive Cologuard results have normal findings, hyperplastic polyps, or non-advanced adenomas on follow-up colonoscopy 3

Comparison to Other Screening Methods

• Cologuard offers better detection of polyps compared to traditional fecal occult blood tests (FOBT) and FIT, which have low sensitivities for detecting colon polyps 1
• Colonoscopy remains the gold standard for polyp detection but has limitations including invasiveness, expense, and suboptimal patient compliance 1, 4
• Other stool-based DNA biomarkers (like methylated SFRP2) have also shown ability to identify patients with precancerous colonic polyps 1

Important Considerations

• A positive Cologuard test requires follow-up with colonoscopy for definitive diagnosis 1
• The appropriate screening interval for Cologuard has not been clearly established due to limited data 1
• The test's primary value is in detecting cancer rather than polyps, though it does detect some advanced adenomas that might be missed by FIT 2
• For patients specifically concerned about polyp detection, colonoscopy remains the most sensitive option 5

Cologuard represents an improvement over traditional stool-based tests for detecting polyps but still misses a significant proportion of advanced adenomas and most non-advanced polyps.