The aim of this project is to assess the impact of a health literacy (HL) intervention combining HL and CRC screening training for general practitioners with a short brochure and video targeting eligible patients to increase CRC screening and other secondary outcomes in four underserved geographic areas in France. The investigators will use a two-arm randomized controlled cluster trial at 8 clusters (2 per area) primarily serving underserved populations across 4 geographic areas in France with 32 primary care physicians and 1024 patients recruited.

Background Colorectal cancer (CRC) is a leading cause of cancer burden worldwide and the third most commonly diagnosed cancer in France (with 44,000 new cases in France each year). Systematic uptake of CRC screening can improve survival rates. However, people with limited health literacy (HL) and lower socioeconomic position rarely participate. The overall goal is to assess the impact of a HL intervention combining HL and CRC screening training for general practitioners with a short brochure and video targeting eligible patients to increase CRC screening and other secondary outcomes in four underserved geographic areas in France.

Methods The investigators will use a two-arm randomized controlled cluster trial at 8 clusters (2 per area) primarily serving underserved populations across 4 geographic areas in France with 32 primary care physicians and 1024 patients recruited. Primary care physicians practicing in underserved areas (identified using the European Deprivation Index and French Deprivation index) will be block-randomized to: 1) a combined intervention (HL and colorectal cancer training + brochure and video for eligible patients) or 2) usual care. The investigators will include all people between 50 and 74 years old who are eligible for CRC screening. The project will follow a community-based participatory research approach. The primary outcome is CRC screening uptake. The project will also include a qualitative needs assessment (focus groups and interviews) prior to finalizing the intervention and to test the acceptability of the combined intervention before the trial. After completing recruitment, semi-structured interviews will be conducted with up to 8 health professionals in each region (up to 24) and 6 to 12 patients per region (up to 48) based on data saturation. The investigators will explore strategies that promote the intervention's sustained use and rapid implementation using the Normalization Process Theory. A regression framework and mediation analyses will be used.

Discussion Limited HL and its impact on the general population is a growing public health and policy challenge worldwide. It has received limited attention in France. A combined HL intervention could reduce disparities in CRC screening, increase screening rates among most vulnerable populations, and increase knowledge and activation (beneficial in the context of repeat screening).

Inclusion Criteria:

• People between 50 and 74 years old who are eligible for colorectal cancer screening and seen by a participating general practitioner.
• People who are able to complete a questionnaire in French, either alone or with help from a caregiver or relative.
• People with intellectual disability will be included as long as they are able to complete a questionnaire alone or with help from a caregiver or relative.

Exclusion Criteria:

- People whose mental health status does preclude participation in the study, as determined by the participating primary care practitioner or their qualified staff.

Masking investigator, research assistants and data analyst