<p>In oncology there is a&#xa0;high demand for scientific evidence due to increasing complexity and rapid and far-reaching innovation. For systematic, time-related, and economic reasons, conducting prospective randomized controlled clinical trials is becoming increasingly challenging for many questions in the areas of diagnostics, treatment, and care. The “fathers” of evidence-based medicine warned against unattainable evidence requirements for good reason, calling for use of the best available evidence to answer a&#xa0;clinical question rather than the theoretically maximum possible evidence. In order to obtain evidence in the context of increasingly genetic and genomic tumor-related differential diagnostics and the rapid development of personalized therapeutic approaches in oncology, greater use must be made of data from real patient care, from statutory and primarily research-related cancer registries, and from billing data from statutory and private health insurance companies. Responsible analysis of this healthcare-related data and interpretation of the results obtained from it require specific scientific approaches, expertise, and experience. For effective and sustainable creation of evidence in oncology, the traditionally good cooperation between oncologists and healthcare researchers must be further intensified.</p>