We present a field study of oncology workflow, involving doctors, nurses and pharmacists at Danish hospitals and discuss the obstacles, enablers and challenges for the use of computer based clinical practice guidelines. Related to the CIGDec approach of Pesic and van der Aalst we then describe how a sub workflow can be described in a declarative workflow management system: the Resultmaker Online Consultant (ROC). The example demonstrates that declarative primitives allow to naturally extend the paper based flowchart to an executable model without introducing a complex cyclic control flow graph.