BACKGROUND: Patient and public involvement (PPI) has become an essential part of health research. There is a need for genuine involvement in order to ensure that research is relevant to patients. This can then improve the quality, relevance, and impact of health research, while at the same time reducing wasted research and in doing so bringing science and society closer together. Despite the increasing attention for this involvement, it is not yet common practice to report on proposed activities. An article reporting planned PPI could provide guidance and inspiration for the wider academic community in future activities. Therefore, this current article aims to describe the way in which PPI principles are incorporated in the research project called "Quality of Life in Oncology: measuring what matters for cancer patients and survivors in Europe (EUonQoL)." This project aims to develop a new set of questionnaires to enable cancer patients to assess their quality of life, entitled the EUonQoL-Kit.

METHODS: The first step is to recruit cancer patients and their informal caregivers as co-researchers in order to train them to collaborate with the researchers. Based on their skills and preferences, they are then assigned to several of the project's work packages. Their individual roles, tasks, and responsibilities regarding the work packages, to which they have been assigned, are evaluated and adapted when necessary. The impact of their involvement is evaluated by both the researchers and co-researchers.

DISCUSSION: PPI is a complex and dynamic process. As such, the overall structure of the research may be defined while at the same time leaving room for certain aspects to be filled in later. Our research is, we believe, relevant as co-researcher involvement in such a large European project as EUonQoL is a new development.