OC-042 Sensitivity Of Annual Faecal Immunochemical Tests For Haemoglobin (fit) For Detecting Advanced Neoplasia In Patients Undergoing Three-yearly Surveillance Colonoscopy – The Fit For Follow-up Study

Abstract

Introduction: With increasing demand for colonoscopy in the NHS Bowel Cancer Screening Programme (BCSP) in England, there is a need for effective non-colonoscopic approaches to surveillance. We have undertaken a study to compare the sensitivity and specificity of a faecal immunochemical test for haemoglobin (FIT) annually for three years with colonoscopy surveillance, in patients diagnosed with intermediate-risk adenomas following a positive faecal occult blood test in the BCSP. Methods: Participants are invited to complete a FIT (OC-SENSOR, Eiken Chemical Co. Ltd.) annually while awaiting their first surveillance colonoscopy. Those testing positive (>40mug Hb/g faeces) are invited to have their three-year colonoscopy brought forward, while those testing negative are sent another FIT a year later until they have completed three rounds of testing. We aim to determine the sensitivity of FIT in detecting colorectal cancer or advanced adenomas (>10mm, or with tubulovillous or villous histology, or with high-grade dysplasia), using colonoscopy as the reference standard. Results: We invited 8009 people to participate in the study, of whom 5945 (74.2%) consented. The positivity rate in Round 1 was 5.8% (347/5945). To date, 310/347 (89.3%) have had an early colonoscopy: 73/310 (23.5%) had advanced adenomas and six (1.9%) had cancer. 35/347 (10.1%) declined an early colonoscopy. To date, in Round 2 we have invited 5264 patients who tested FIT negative in Round 1: 5017 (95.3%) completed a second FIT and 225/5017 (4.5%) tested positive. To date, 179/225 (79.6%) have received an early colonoscopy: 32/179 (17.9%) had advanced adenomas and six (3.4%) had cancer. 17/225 (7.6%) declined an early colonoscopy. To date, in Round 3, we have invited 2263 participants who had negative FIT tests in Rounds 1 and 2 with 2095 (92.6%) returning a kit. 83/2095 (4.0%) tested positive. All participants in Round 3 are due to attend their surveillance colonoscopy in the coming months. Satisfaction with the study was high among those who completed a questionnaire, with 94.6% (4488/4743) and 96.3% (3657/3796) of FIT-negative participants in Rounds 1 and 2, and 91% (252/277) of FIT-positive participants in Round 1 stating that they would complete another kit in future. Conclusion: Compliance with the study was high, and the majority of participants reported that they would use FIT again. Almost a quarter (23.5%) of patients in Round 1 who had an early colonoscopy had advanced adenomas, falling to 17.9% in Round 2. Rounds 2 and 3 are ongoing.