Most participate in faecal immunochemical test-based colorectal cancer screening out of curiosity about their chances of developing cancer.

Several clinical trials have shown that colorectal cancer (CRC) screening can reduce cancer deaths. Its effectiveness is affected by the participation level. To develop targeted invitations, we need to understand why individual persons decide to participate. To evaluate reasons for participation among persons invited for faecal immunochemical test-based CRC screening, a total of 10,265 asymptomatic persons aged 50-75 years were invited to a Dutch CRC screening pilot (2008-2009). Reasons for participation were elicited by a questionnaire. A total of 3554 (66%) participants returned the questionnaire. Obtaining more certainty about the chances of developing cancer (ticked by 88%) and the occurrence of cancer in the family or the circle of acquaintances (18%) were the most frequently selected reasons for participation. We also explored reasons for nonparticipation among nonparticipants. In this subgroup, comorbidity and the absence of symptoms were the most frequently reported reasons for declining to participate, but the response rate was low. The vast majority of the participants decided to take up the screening because they wanted to know more about their chances of developing cancer.