Background: Colorectal cancer (CRC) imposes a large disease burden in Europe. In 2021, CRC accounted for 12% of both new cancer diagnoses and cancer deaths in the European Union (EU). While screening remains a cornerstone of CRC prevention, screening programs also represent a unique platform to promote cancer?preventive behaviors. Diet and lifestyle are major determinants of CRC risk, with roughly half of all cases attributable to these factors. Addressing diet and lifestyle in a screening context therefore has great potential — not only to lower CRC incidence, but also to contribute to broader disease prevention. The recent update of the European Code Against Cancer (ECAC5) highlights this opportunity; however, implementation at population scale requires the development and evaluation of scalable, cost?effective interventions that can be seamlessly integrated into existing screening practices.

Objectives: In KoloPrev we will examine the effect of a personalized digital diet and lifestyle intervention embedded within CRC screening on cancer?preventive behaviors over a two?year period (n = 16,000). We will also investigate participant perceptions (detailed in a separate abstract), overall and sociodemographic reach, as well as potential effects on screening participation rates. In the long term (through 2040), we will monitor potential lasting effects of the intervention on cancer incidence and mortality.

Methods: KoloPrev (NCT07135115) is a multi?arm, parallel?group randomized controlled trial (RCT) nested within the Norwegian national CRC screening program. The study comprises five groups: standard care (“screening as usual”), a control arm, and three intervention arms with varying levels of follow?up and support. The core of the intervention is the Digikost tool, a digital questionnaire that maps diet and lifestyle and instantly provides personalized feedback. Participants in the highest?intensity group will additionally be offered individual telephone counseling by master’s?level clinical nutrition students and invited to regular webinars. The primary outcome is change in cancer?preventive behaviors measured by a seven?point composite score based on the 2018 World Cancer Research Fund (WCRF) recommendations, with an additional component for tobacco avoidance. In addition to the overall change in the composite score, we will examine effects on each behavioral component and explore differential effects across sociodemographic subgroups.
 
Results: With study start scheduled for February 2026 and a four?month recruitment window, we anticipate randomizing 16,000 participants by summer 2026. Owing to the study’s digital, automated design, baseline data on adherence to cancer preventive behaviors, as well as initial measures of participant perceptions, reach and any potential influence on screening participation, will be available at that time. These early indicators will provide an initial assessment of the intervention’s potential and feasibility.

Conclusions: In KoloPrev we evaluate the behavior change potential of a low threshold digital intervention targeting diet and lifestyle within CRC screening. Combined with data on acceptability, uptake, and participant characteristics, the results will inform whether this approach could be one way of effectively operationalizing the ECAC5 recommendation of using CRC screening programs (and screening programs more broadly) as a platform to promote healthy living.