Mo1177 Participation, FIT-Result and Yield in Three Rounds of Biannual FIT-Based Screening in the Netherlands

Abstract

Background Most European colorectal cancer (CRC) screening programs rely on fecal occult blood testing (FOBT), of which fecal immunochemical tests (FIT) have the best accuracy and adherence rates. The effectiveness of these FOBT-based programs is not only influenced by the participation and yield of the initial screening round, but also by program adherence during consecutive rounds. FIT sensitivity is relatively low and is increased by repeated screening rounds. We aim to evaluate the participation rate, yield and progression of FIT screening for CRC over three rounds of CRC screening . Methods A total number of 10,050 average risk individuals were invited to participate in a third round of biennial FIT-based CRC screening, using OC-Sensor with a cut-off of 50 ng/ml buffer(or 10 ug/mg feces). Invitees were between 50 and 75 years of age. They received an invitation, including an information leaflet, a FIT-test, and a pre-paid return envelope. All FIT-positives were recommended to undergo a colonoscopy unless contraindicated. Colonoscopy findings were classified as CRC, advanced adenoma, advanced neoplasia (CRC plus advanced adenoma) or other. Participation rates, FIT positivity rate, FIT positive predictive value and mean level of FIT-result were calculated, and compared to the results of the first two screening rounds. Results Within this cohort, 5,671 invitees (56%) returned the FIT in this third screening round, compared to 52% in the second round and 56% in the first round (p ,0.001). Overall, 377 (6.8%) of the third round participants had a positive FIT result, versus 7.4% in the second round and 8.1% in the first round (p ,0.01). Of the FIT positives, 316 (84%) underwent colonoscopy. 59 could not undergo colonoscopy because of medical reasons or did not want to undergo colonoscopy. 88 participants had at least one advanced adenoma (28% of positives) and 17 had cancer (5%). The FIT positive predictive value for advanced neoplasia was 30%, compared to 44% in the second round and 55% in the first round; a significant decline (p,0.01) The average FIT result decreased in consecutive screening rounds from 430 ng/ml in the first round to 370 ng/ml in the second and 348 ng/ml in the third round. This decrease was not significant (round one versus round 2 p= 0.16; round one versus round three: 0.08). Conclusion In consecutive CRC screening rounds with FIT, the participation rate stays stable, but both FIT positivity rate for advanced neoplasia and its positive predictive value decline significantly. The average concentration of Hb in Feces decreased over several rounds of FIT based screening, though not significant.