Risk of colorectal cancer in patients with positive results of fecal immunochemical test performed within 5 years since the last colonoscopy.

Background/aims: Annual fecal immunochemical tests (FITs) are often repeated within the recommended colonoscopy surveillance intervals. However, it remains unclear whether interval FITs are useful. To answer this question, we assessed the risk of colorectal cancer (CRC) according to the interval from the last colonoscopy to an FIT.

Methods: Using the Korean National Cancer Screening Program database, we collected data on patients who underwent FITs in 2011. Patients with positive FIT results were classified into three groups according to their previous colonoscopy interval: 0.5 to 5 years (group 1), 5 to 10 years (group 2), and ≥ 10 years or no colonoscopy (group 3). CRC incidence was defined as CRC diagnosed within 1 year after an FIT.

Results: Among 177,660 patients with positive FIT results, the incidence of CRC in groups 1, 2, and 3 was 0.72% (n = 214/29,575), 1.28% (n = 116/9,083), and 3.88% (n = 5,387/139,002), respectively. The age- and sex-adjusted risk for CRC was higher in groups 2 (odds ratio [OR], 1.79; 95% confidence interval [CI], 1.43 to 2.25) and 3 (OR, 5.56; 95% CI, 4.85 to 6.38) than in group 1. Among patients who did and did not undergo a polypectomy during the previous colonoscopy, those in group 2 had a higher rate of CRC than those in group 1 (without polypectomy: 1.15% vs. 0.63%; OR, 1.79; 95% CI, 1.37 to 2.34) (with polypectomy: 2.37% vs. 0.93 %; OR, 2.30; 95% CI, 1.44 to 3.69).

Conclusion: In patients with positive FIT results who had undergone a colonoscopy within the past 5 years, the risk of CRC is very low, regardless of whether a polypectomy was performed, suggesting that interval FITs are not useful.