Background: The Dutch guideline on breast cancer treatment shows several grey areas, where no clear recommendation is given on the radiotherapy options, but where the advice is to discuss the treatment of choice with the patient. Currently, patients are exposed to different information given by the professionals' personal styles of informing patients. The challenge for all oncological professionals is to give clear, structured, and neutral information on the pros and cons of the treatment option(s) in the context of the natural course of the disease to the patient; to elicit patients' needs and preferences. How and which information should be shared in a decision aid is up for investigation, as well as how this should best be implemented.