A Predictive Model Based on Quantitative Fecal Immunochemical Test Can Stratify the Risk of Colorectal Cancer in an Organized Screening Program

Background & aims: A significant number of post fecal immunochemical test (FIT) colonoscopies in European-organized colorectal cancer (CRC) screening programs are performed beyond the recommended 31-day threshold due to overburdened colonoscopy services. We aimed to develop a simple predictive model to stratify CRC risk of FIT+ patients.

Methods: In a cohort of screenees undergoing colonoscopy following a positive (≥20 μg hemoglobin/g feces) OC-sensor FIT result between 2004 and 2019, we derived and validated logistic regression-based models including variables independently associated with CRC and advanced neoplasms. Odds ratios (ORs) and 95% confidence intervals (CIs) were reported.

Results: Overall, 40,276 patients (46% female; mean age, 66 ± 4 years) undergoing post FIT colonoscopy were included. Variables independently associated with CRC were age ≥70 years (OR, 1.20; 95% CI, 1.03-1.40), male sex (OR, 1.23; 95% CI, 1.11-1.37), fecal hemoglobin level (50-199 μg/g: OR, 2.84; 95% CI, 2.47-3.27; ≥200 μg/g: OR, 6.91; 95% CI, 5.99-7.98), and first round of FIT (OR, 1.53; 95% CI, 1.35-1.73). The discriminative ability of the model was good (area under the receiver operating characteristic, 0.75; 95% CI, 0.73-0.77) in the validation cohort. Applying the model would lead to over two-thirds decrease in delayed CRC diagnoses, considering various scenarios of timely colonoscopy scheduling after FIT+.

Conclusions: We derived and validated a predictive model for risk stratification of patients with positive FIT in a large CRC screening cohort. Applying our model in screening practice would allow policy makers to effectively prioritize FIT+ individuals based on the risk of CRC, substantially reducing the rate of delayed CRC diagnosis.