SP3.12 - Effect of Anticoagulants on Faecal Immunochemical Tests (FITs) in Bowel Cancer Screening

Abstract Background Bowel cancer screening in the United Kingdom is based on the faecal immunochemical test (FIT). Eligible participants sometimes use anticoagulants which may stimulate bleeding from benign lesions affecting the screening performance of FITs for colorectal cancer. We aimed to evaluate the effectiveness of FITs in screening for colorectal cancer for patients taking anticoagulants. Methods This was a retrospective study of FIT positive patients on anticoagulation who underwent colonoscopy or CT colonoscopy between October 2022 and June 2023. The threshold for a FIT positive result was 150µg Hb/g of faeces for asymptomatic patients and 10µg Hb/g of faeces for symptomatic patients. Histology reports were reviewed for the presence of colorectal neoplasms and advanced adenomas (defined as adenomas with high-grade dysplasia, villous histology, or ≥10mm in size). Results A total of 57 patients were included- 38 used a direct oral anticoagulant (DOAC), 3 used warfarin, 15 used clopidogrel or ticagrelor, and 1 used dabigatran. Colorectal cancer was identified in 8.8% of individuals (5 out of 57) and advanced adenoma in 17.5% of individuals (10 out of 57). Use of anticoagulants was associated with a positive predictive value for advanced neoplasia (PPVAN) of 26.3%. Conclusion FIT accuracy as a surrogate marker for advanced neoplasia was not affected by the use of anticoagulants when compared with the current literature. Suspension of anticoagulation prior to FIT screening is not recommended. Further studies investigating the dosage and class of anticoagulation on FIT accuracy for bowel cancer screening may be warranted.