Faecal immunochemical test in subjects not attending screening computed tomography colonography and colonoscopy in a randomized trial

The aim of this study was to evaluate the participation and yield of the faecal immunochemical test (FIT) in nonattendees for computed tomography colonography (CTC) or optical colonoscopy (OC) screening, in the setting of a randomized trial. In the SAVE trial, 16087 individuals were randomly assigned and invited to one of four interventions for colorectal cancer screening: (i) biennial FIT for three rounds; (ii) reduced-preparation CTC; (iii) full-preparation CTC; and (iv) OC. Nonattendees of reduced-preparation CTC, full-preparation CTC and OC groups were invited to FIT. Here, we analysed the participation rate and the detection rate for cancer or advanced adenoma (advanced neoplasia) of FIT among nonattendees for reduced-preparation CTC, full-preparation CTC and OC. Nonattendees were 1721 of 2395 (71.9%) eligible invitees in the reduced-preparation CTC group, 1818 of 2430 (74.8%) in the full-preparation CTC group and 883 of 1036 (85.2%) in the OC group. Participation rates for FIT were 20.2% (347/1721) in nonattendees for reduced-preparation CTC, 21.4% (389/1818) in nonattendees for full-preparation CTC and 25.8% (228/883) in nonattendees for OC. Differences between both CTC groups and the OC group were statistically significant (P≤0.01), whereas the difference between reduced-preparation and full-preparation CTC groups was not statistically significant (P=0.38). The detection rate of FIT was not statistically significantly different among nonattendees for reduced-preparation CTC (0.9%; 3/347), nonattendees for full-preparation CTC (1.8%; 7/389) and nonattendees for OC (1.3%; 3/228) (P>0.05). Offering FIT to nonattendees for CTC or OC increases the overall participation in colorectal cancer screening and enables the detection of additional advanced neoplasia.