Background: Effective primary cancer prevention depends on translating scientific evidence into actionable public health communication. Adolescence is a critical life stage for establishing lifelong health behaviors, yet evidence-based prevention guidelines are often disseminated without systematic optimization of delivery strategies. Most existing studies focus on intervention content alone, with limited attention to how dissemination format, length, and content interact under real-world conditions. Under the World Code Against Cancer framework, China released the China Code Against Cancer to guide population-wide prevention. From an implementation science perspective, this study evaluates the efficacy of different dissemination strategies in enhancing adolescents' cancer prevention knowledge, with the goal of informing precision health communication.

Objectives: To assess the main effects and interactions of dissemination format, length, and content on adolescents' acquistion of primary cancer prevention knowledge, and to identify the optimal combination of strategies for maximizing knowledge acquisition.
Methods: We conducted a field-based quasi-experimental study using a three-factors between-subjects design in Shandong, China in 2024. The three factors were: (1) Format (text-only vs. text + image), (2) Length (brief vs. Detailed), (3) Content (preventive behaviors, risk factors, or both), yielding 12 intervention combinations plus a no-intervention control group. A total of 7,245 middle school students (aged 12 and 18) were randomly assigned to receive printed leaflets corresponding to these designs. Primary cancer prevention knowledge was measured using the Core Knowledge of Primary Cancer Prevention Questionnaire developed by the team (Cronbach’s α = 0.87). Overall intervention effects were evaluated using non-parametric tests and generalized linear models to estimate main effects and interaction effects.

Results: The baseline median knowledge score was 47.0 (IQR: 41.5-52.0). Post-intervention, the score increased to 50.5 (IQR: 44.5-54.5), with non-parametric tests confirming a significant overall improvement (P < 0.001). The three-way interaction among format, length, and content was not significant (P = 0.36); however, all two-way interactions were statistically significant (P < 0.01), indicating synergistic effects among dissemination elements. Specifically, when text was combined with images, detailed explanations significantly enhanced intervention effectiveness (P <0.01). Detailed explanations were more effective than brief messages when content focused on risk factors or combined content (P <0.01), whereas images alone did not confer additional benefit across content types. Ranking of intervention combinations showed that text + image format with detailed explanations focusing on risk factors achieved the greatest knowledge gain (LSMean = 4.26, 95% CI: 3.54~4.97).
Conclusions: Effective implementation of cancer prevention guidelines depends not only on what information is delivered, but also on how it is communicated. For adolescents, detailed, science-based explanations of cancer risk factors are particularly effective in improving prevention knowledge. Optimizing the synergy among dissemination format, length, and content is critical for maximizing implementation effectiveness and provides empirical guidance for precision public health communication.