Three-year outcomes and alternative diagnoses in FIT-positive symptomatic patients without colorectal cancer: a real-world cohort study

Objective Faecal immunochemical testing (FIT) is widely used to triage symptomatic patients for colorectal cancer (CRC), but it is not disease-specific and may reflect a range of alternative bleeding-related pathologies. We aimed to characterise alternative diagnoses and their association with FIT levels in FIT-positive symptomatic patients without CRC over 3 years of follow-up. Method We performed a retrospective cohort study of 1056 FIT-positive symptomatic patients without CRC. FIT distributions were summarised descriptively by diagnosis group. Associations between FIT and diagnosis were assessed using multivariable logistic regression with log10-transformed FIT, adjusted for confounders. Results The cohort had mean age of 64.2 years and median FIT was 51 µg haemoglobin (Hb)/g faeces. The most frequent diagnoses were diverticulosis (n=475) and benign colorectal polyps (n=387). Median FIT values were highest in inflammatory bowel disease (IBD) (311), vascular disease (284) and radiation colitis (180), and lowest in normal findings (31). Increasing FIT was independently associated with IBD (OR 3.38, 95% CI 1.92 to 5.95), vascular disease (3.93, 1.76 to 8.76), benign upper gastrointestinal (GI) conditions (2.06, 1.28 to 3.32) and perianal disease (1.89, 1.37 to 2.60), while normal findings were less likely (OR 0.59, 95% CI 0.43 to 0.81). Completion of gold-standard colorectal investigations and documented safety-netting occurred in 64% and 52% of patients, respectively. Conclusion FIT appears to reflect GI bleeding burden rather than CRC alone, supporting its broader interpretive value while reinforcing the need for appropriate downstream investigation and safety-netting. A small number of subsequent CRCs were identified after initially negative or absent investigations.