Colonoscopy after a Positive Stool-based Test for Colon Cancer Screening: Moving Toward a Better Understanding of What to Expect

Stool-based tests for colorectal cancer, including fecal immunochemical testing (FIT) and multitarget stool DNA testing (mt-sDNA), are among the recommended first-line screening options for patients at average risk for colorectal cancer and offer advantages over colonoscopy. However, stool-based tests have high false-positive rates, and the expected yield of colonoscopy after positive FIT compared with positive mt-sDNA is not well studied. As discussed in this issue of Cancer Prevention Research, the presence of a precancerous lesion in the majority of cases with either positive stool-based test is expected. In addition, a positive mt-sDNA is associated with a higher risk for finding any neoplasia on colonoscopy compared with positive FIT, and particularly associated with higher prevalence of clinically relevant serrated polyps compared with positive FIT. Further research is needed on what to expect from positive stool-based testing on average risk 45-49 years old patients, the newest cohort indicated for colorectal cancer screening.

Automated summary

Stool-based tests for colorectal cancer are recommended as first-line screening options, but have high false-positive rates. A positive stool-based test result may indicate the presence of a precancerous lesion. Positive mt-sDNA is associated with a higher risk for finding tumors on colonoscopy, especially clinically relevant serrated polyps, compared with positive FIT.