Personalised Behavioural Intervention in Cancer Screening Programmes

CANVIA is a personalised behavioural intervention designed to support adherence to dietary and lifestyle recommendations for cancer prevention. The intervention is based on the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) Cancer Prevention Recommendations and uses the WCRF/AICR Screener to assess individual adherence, generate personalised feedback, and tailor intervention intensity and content.

This study corresponds to the prospective feasibility evaluation of CANVIA. It will be conducted within population-based breast and colorectal cancer screening programmes in Palma, Mallorca, Spain, among adults aged 50 to 69 years. The purpose of the study is to evaluate whether CANVIA is feasible, usable, acceptable and engaging in this public health setting, and to explore its preliminary efficacy for improving adherence to WCRF/AICR cancer prevention recommendations.

The study will be conducted in two sequential quantitative phases, followed by an embedded qualitative component. First, a single-arm proof-of-concept phase will include approximately 20 to 30 participants. This phase will assess the operational readiness of the recruitment pathway, study procedures, data collection system, mobile application and intervention delivery. Findings from this phase will be used to refine study procedures and digital tools before initiating the randomised pilot feasibility trial.

The subsequent pilot trial will use a three-arm, parallel-group, randomised design with an anticipated enrolment of 132 participants. Participants will be randomly assigned in a 1:1:1 ratio to one of three groups: a control group receiving a personalised baseline feedback report, a mobile app-based CANVIA intervention, or the same mobile app-based intervention combined with structured support from health professionals.

In the active intervention groups, the WCRF/AICR Screener score will be used to classify participants according to their need for lifestyle change and to tailor the intensity and target behaviours of the intervention. The mobile app-based intervention will include tailored messages, educational resources and app-based goals or challenges. Participants receiving additional professional support will also have structured contacts focused on reviewing personalised recommendations, supporting goal setting, monitoring progress, providing feedback and addressing barriers to change.

The intervention will last six months and will be organised into two three-month blocks. The WCRF/AICR Screener will be repeated at Month 3 to monitor changes in adherence and, where appropriate, to update intervention intensity and target behaviours for the second intervention block. Study assessments will be conducted at baseline, Month 3 and Month 6.

The planned pilot trial sample size is 132 participants, with 44 participants per arm. This sample size allows for up to 30% loss to follow-up and is intended to support the assessment of feasibility outcomes and exploratory between-group comparisons in WCRF/AICR Screener score at Month 6.

Main evaluation domains will include feasibility, usability, acceptability, app engagement and preliminary efficacy. Analyses of the pilot trial will follow the intention-to-treat principle. Preliminary efficacy in improving adherence to cancer prevention recommendations will be explored using a linear mixed model including study arm, time, and the arm-by-time interaction; planned pairwise comparisons at Month 6 will be reported with 95% confidence intervals.

Focus groups conducted at Month 6 with participants from the intervention groups will explore participant experiences, barriers and facilitators to engagement, and suggestions for improving the intervention and study procedures before future larger-scale evaluation. Qualitative data from focus groups will be analysed thematically.

Inclusion criteria

• Women and men participating in the breast and/or colorectal cancer screening programmes within the Sector Sanitari Ponent, Hospital Universitari Son Espases.
• Aged 50 to 69 years.
• No history of cancer.
• No evidence of an active tumour process, defined as a negative screening result and/or negative complementary tests, as applicable.
• Able and willing to provide written informed consent prior to any study procedure.
• Sufficient verbal and reading comprehension of Spanish and/or Catalan to complete study procedures and questionnaires.
• Access to a smartphone with internet connection and sufficient storage, and ability to install and use the study application.
• Availability to attend the IdISBa Clinical Trials Unit at Hospital Universitari Son Espases for scheduled in-person visits, as agreed with the research team.

Exclusion criteria

• Any diagnosed condition that severely affects dietary intake or requires medically prescribed restrictive nutrition, such as an eating disorder, severe renal or gastrointestinal disease, or parenteral nutrition.
• Any diagnosed condition that severely limits the ability to perform light or moderate physical activity.
• Excessive alcohol consumption, defined as more than 6 standard units per day, or problematic substance use.
• Concurrent participation in another clinical trial that, in the investigator's judgement, may interfere with the present study outcomes.
• Body mass index <18.5 kg/m² or >40 kg/m²