Background
Including diet- and lifestyle interventions within routine cancer screening offers an important arena to improve health behaviour at a population level. Poor diet, physical inactivity, and tobacco use are important modifiable risk factors for colorectal cancer (CRC). The European Code Against Cancer (5th edition, ECAC5) explicitly recommends using screening programs to promote healthy living to reduce the incidence of CRC and other non-communicable diseases.

In the KoloPrev randomized controlled trial (RCT), we will investigate whether a low-threshold, digital intervention (Digikost) that delivers personalized feedback on diet and lifestyle can improve cancer-preventive behaviours over a two-year period within the Norwegian CRC screening program. The study is designed as a multi-arm parallel group RCT with three intervention groups who will receive varying degrees of follow-up and support (more details in a separate abstract). Knowledge on how the participants perceive and experience the intervention is important for potential future implementation. We will therefore conduct a qualitative interview study.

Objectives
Investigate the acceptability of a digital diet- and lifestyle intervention administered at CRC screening.

Methods
To explore acceptability of the intervention as perceived by the participants in the KoloPrev RCT (NCT07135115), individual qualitative interviews will be conducted using semi-structured interview guides. Acceptability is conceptualized as an implementation outcome and is an important construct to explore that may contribute toward the overall success of the intervention. The interviews will be conducted with a subsample of the participants who receive the intervention during the spring of 2026. Each participant will be interviewed two times. The first interview will be conducted shortly after baseline to capture their initial reactions to receiving the intervention in the screening setting. The second interview will be conducted approximately one month later to understand their views of the intervention over time.

Acceptability often varies depending on factors such as socio-demographic background, gender and geographical distribution. Purposive sampling will be used to achieve maximum variety. The number of participants will be decided based on established guidelines as part of the concept of information power. We expect to include 10-15 participants.
  
The interviews will be conducted either in person or via zoom, and will be audio recorded, transcribed verbatim and uploaded to NVivo. We will follow the principles of reflexive thematic analysis for analysing the data.

Results
Recruitment and data collection is scheduled to begin in February 2026. We will complete both rounds of interviews by the end of April 2026, with preliminary results from the baseline interviews expected in May 2026.

Conclusions
Findings will give important knowledge on the acceptability of including a personalized digital diet- and lifestyle intervention in the national CRC screening program, and may guide optimization and potential future implementation and scale up.