Assessing and comparing patient engagement in clinical cancer research: A cross-regional analysis between Europe and Japan using a structured evaluation tool

Meaningful patient engagement (PE) is increasingly recognized as a critical element of clinical cancer research. Policy frameworks in Europe and Japan reflect growing support for involving patients in research and policymaking. However, tools to assess the actual implementation of PE in clinical trials remain limited. This study introduces a structured, self-evaluation tool for principal investigators (PIs) to assess PE and compares its application to academic trials across Europe and Japan. A two-dimensional matrix was developed to evaluate PE across eight key research steps—research priorities, fundraising, protocol development, informed consent, ethical review, investigator meetings, reporting, and regulatory submission—against five engagement levels (0: none to 4: co-creation). The tool was refined to ensure linguistic and contextual applicability in both regions. A structured questionnaire incorporating the matrix was distributed to PIs identified from public databases. Statistical analyses were conducted to compare PE practices between both regions. Among 178 European and 123 Japanese trials, PI response rate were 24.2% (n=43) and 52.0% (n=64), respectively. Across all research steps, 60.7% of European and 80.6% of Japan trials contained no PE. However, PE was reported in at least one step in 86.0% of European and 39.1% of Japanese trials. When engaging, European trials showed higher levels in protocol development, informed consent, ethical review, and reporting steps than Japan ( p < 0.001 for all). This study developed a simple, structured tool to assess PE and applied it to trials in Europe and Japan. It revealed regional differences across culturally and structurally distinct systems, demonstrating its value for cross-context comparison and broader application. By enabling structured assessment and monitoring of PE, this tool supports the implementation of engagement policies across regions. Its adaptability may foster shared learning and cross-border collaboration, especially in regions where engagement frameworks are still emerging. • Establishment of a structured and simple self-evaluation tool for researchers to measure patient engagement in cancer research, allowing a comparison of patient engagement across research step between countries • Tool tested on principal investigators of academic cancer clinical trials selected from publicly available trial databases in Europe (EudraCT) and Japan (UMIN and jRCT) (period: 2018-2022) • Patient engagement levels significantly higher in Europe than Japan • Findings supporting policy efforts and future adaptations in culturally, geographically and resource-diverse contexts