Tumor boards are multidisciplinary meetings of medical experts who consensually decide about diagnosis and treatment recommendations for cancer patients. They are decisive for treatment quality and patient survival. At the same time, they are highly resource-intensive, time-consuming, and complex to schedule. Hospitals compensate this by scheduling tumor boards well in advance. However, this causes delays in cancer treatment and psychological stress for patients. To address this issue, ad-hoc tumor boards may constitute a viable alternative to traditionally scheduled ones if they are properly supported by information systems and effectively integrated into physicians’ busy and unpredictable work day. In this design science research, we therefore propose (1) a prototypical process of carrying out ad-hoc tumor boards and (2) design features of an information system that supports ad-hoc tumor board scheduling and fosters the intrinsic motivation of physicians to participate in them. The development of the process and the design features has been informed by interviews and surveys conducted in 11 hospitals in Europe. We are currently developing the information system. For future evaluation, we outline the properties of a study with students and a clinical trial.