The most common colorectal cancer (CRC) screening methods are colonoscopy, flexible sigmoidoscopy (FS), and fecal immunochemical testing (FIT). The diagnostic yield of any screening method is dependent on participation, and endoscopic screening consistently shows lower participation rates compared to FIT-based screening. In this analysis of three randomized studies, 30,052 asymptomatic patients aged 50 to 74 years were invited for CRC screening and assigned to either 4 rounds of FIT (15,046 patients invited), once-only FS (8,407 patients invited), or once-only colonoscopy (6,600 patients invited), to determine the number of advanced neoplasias (AN) detected with each test. Patients with positive FIT results (≥10 μg Hb/g feces), or FS patients found to have a polyp ≥10 mm, adenoma with ≥25% villous histology or high-grade dysplasia, sessile serrated adenoma, ≥3 adenomas, ≥20 hyperplastic polyps, or invasive CRC were referred for colonoscopy. Researchers found that the participation rate was significantly higher for FIT screening (77%) than for FS (31%, p<0.001) or colonoscopy (24%, p<0.001). In the intention-to-screen analysis, the cumulative diagnostic yield of AN was higher with FIT screening (4.5%, 95% CI 4.2% to 4.9%) than with colonoscopy (2.2%, 95% CI, 1.8% to 2.6%) or FS (2.3%, 95% CI, 2.0% to 2.7%). In the as-screened analysis, colonoscopy detected more AN (9.1%, 95% CI 7.7% to 10.7%) than FS (7.4%, 95% CI 6.5% to 8.5%) and FIT (6.1%, 95% CI 5.7% to 6.6%). However, CRC detection rates were similar for FIT (0.8%, 95% CI 0.6% to 0.9%), FS (0.5%, 95% CI 0.3% to 0.9%) and colonoscopy (0.6%, 95% CI 0.3% to 1.2%). Among invitees, the rate of interval CRC development was 0.13% in patients with a negative result from the FIT, 0.09% in patients with a negative result from flexible sigmoidoscopy, and 0.01% in patients with a negative result from colonoscopy. A limitation of this study was that those invited for primary endoscopic screening were only invited once, as compared with those screened with FIT who were approached biennially, which may have impacted participation rates. In summary, this study suggests that FIT screening has a higher diagnostic yield for AN compared to endoscopic screening, despite significantly fewer colonoscopies.
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