What Interval Between a Positive Fecal Immunochemical Test and Follow-Up Colonoscopy Is Safe?

How quickly after a positive fecal immunochemical test (FIT) should colonoscopy be performed? In this retrospective cohort study, researchers looked at risk for any colorectal cancer (CRC) or advanced (stage III or IV) CRC in patients with positive FIT screening who underwent follow-up colonoscopies in a large California healthcare system. Among 1.26 million screened patients, about 107,000 had positive FITs, about 70,000 underwent colonoscopy, and 2191 cancers were found. Median time to follow-up colonoscopy was 37 days.

When colonoscopy was performed during the 30 days after a positive FIT, any CRC and advanced CRC were detected in 3.0% and 0.8% of patients, respectively. These detection rates remained similar for colonoscopies performed d…