Abstract / Summary
Abstract Background Mobile outreach programmes may bring cancer prevention and organised screening information closer to rural communities, but their effects depend on interactions with local contexts and actors. This study aimed to explain how, for whom and under what circumstances the Bergo’Bus programme fostered engagement with cancer prevention and organised screening. Methods We conducted a realist evaluation informed by RAMESES II. An initial programme theory was developed through a realist review of cancer outreach literature published between 2013 and 2023. It was then refined through document analyses, participant observations and qualitative semi-structured interviews with stakeholders across eight departments of Nouvelle-Aquitaine. Data were analysed iteratively as Intervention-Context-Actor-Mechanism-Outcome configurations. Results The literature-derived theory primarily framed outreach as a means of producing individual change through increased awareness, knowledge, motivation and screening engagement. The field study confirmed five mechanisms supporting initial beneficiary engagement: convenience and visibility, social proof and norm activation, trust and psychological safety, personal relevance, and self-efficacy and navigation confidence. These mechanisms generated immediate outcomes, including spontaneous contact, questions, improved understanding and intentions to act, but rarely translated into screening participation or sustained preventive behaviour. This was constrained by the single-visit format, limited follow-up, geographical barriers, privacy concerns and restricted data sharing. The most distinctive empirical outcomes occurred at community and organisational levels, revealing a sixth mechanism: bridge-building and collective efficacy. By forging connections, Bergo’Bus appears to have strengthened cross-sector relationships, resource sharing, professionals' willingness to participate in future local initiatives, and the local dissemination of prevention messages. The refined programme theory therefore shifted from expected individual behaviour change towards a catalytic model centred on community empowerment and strengthened local prevention capacity. Conclusions Bergo’Bus appears to have acted as a catalyst for community mobilization and local prevention networks. Under a single-visit model, its main observable contribution was not sustained individual behaviour change but the strengthening of collective capacity for cancer prevention. Empowerment and strengthened local prevention capacity should therefore be considered core outcomes of rural outreach programmes, alongside resident-level engagement. Longer-term evaluation is needed to examine whether and how these collective capacities are sustained and what further locally relevant outcomes they generate.