SENSITIVITY OF FAECAL IMMUNOCHEMICAL TEST FOR COLORECTAL CANCER SCREENING AND RISK FACTORS FOR INTERVAL CANCER: A FRENCH POPULATION-BASED STUDY

Aims Faecal immunochemical test (FIT) is intended to detect pre-symptomatic lesions to reduce the incidence and mortality of colorectal cancer (CRC). The objectives of this study were to determine the FIT sensitivity, whether diagnostic circumstances had an impact on treatment and survival, and risk factors for interval cancer (IC).

Methods This population-based study evaluated the 2016-2017 CRC screening campaign in Finistère, France. CRCs were classified according to diagnostic circumstances: screen-detected CRC (SD-CRC), CRC with delayed diagnosis, FIT-IC, Post-colonoscopy IC, CRC in non-responders and CRC in the excluded population.

Results The FIT sensitivity for invasive CRC was 80.5%. The median time from FIT to diagnostic colonoscopy was 72 days for SD-CRCs, 389 days for FIT-ICs, and 862 days for post-colonoscopy ICs. SD-CRCs were more frequently treated with endoscopic and surgical resection alone (60.9%), as opposed to FIT-ICs, which were frequently treated with surgery combined with chemotherapy or radiation therapy (70%). Disease-specific 3-year survival was higher in the SD-CRC group (94%) than in the FIT-IC group (73%), non-responders (67%) and excluded subjects (78%; p<0.0001). In multivariate analysis, stage III (OR:2.78) and IV (OR: 3.79), proximal (OR:5.00) and rectal locations (OR:7.73) were risk factors of being diagnosed with FIT-IC rather than SD-CRC. The FIT positivity threshold maximizing the sum of sensitivity and specificity was found to be 17µg/g, with 14 additional invasive CRCs diagnosed.

Conclusions Our study confirms the good sensitivity of FIT. SD-CRCs are primarily early-stage CRCs accessible to less invasive curative treatments and therefore with better survival.

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Publication History

Article published online:
14 April 2022