Factors related to the participation and detection of lesions in colorectal cancer screening programme-based faecal immunochemical test

Background: The overall aim of this study was to describe trends in participation rates and detection of lesions in a colorectal cancer (CRC) screening programme, during three rounds, using faecal immunochemical test (FIT). Methods: National registers were used to collect data on invitations for CRC screening in the Basque Country (Spain) from 2009 to 2014. Information about participation, age, gender and lesions in each round were collected. Results: A total of 961.533 individuals were included in the analysis; respectively, 584.950, 298.143 and 78.440 in the first, second and third rounds. The average participation rate was 68.4% (66.8, 70.4 and 72.3%, respectively by round; P < 0.001) and the positivity rate was 6.3% (7, 5.5 and 5.4%, respectively by round; P < 0.001). The participation rate increased significantly with age and was found to be higher in women versus men. A total of 15.144 advanced adenomas and 2.131 CRCs were diagnosed, leading to a detection rate of 23.9 and 3.4‰, respectively. Regarding gender, men had the highest rates in all periods and rounds. The detection rate of advanced neoplasia was lower in the regular when compared with irregular paricipants. Conclusions: In a CRC screening, this organization obtained high FIT participation rates. Older participants and women were associated with a higher participation. The detection rate of lesions was higher in men, independent on age and round.