Milea Timbergen

329 expected effects of the treatment and this should be individually established for each clinical trial. Second, trial information should be presented as objective as possible to minimize influence on treatment decisions and HRQoL-issues. This could be established by using standardized information videos to inform patients about the study design, potential adverse effects and trial endpoints. Third, the balance between accurate assessment of HRQoL and patient response burden must be evaluated carefully; as too many questionnaires and/or to many questions can lead to a decrease in response rates and missing data 29 . Fourth, the research team should establish a baseline HRQoL-value for their cohort and have consensus on the definition of the desirable ‘effect’ on HRQoL of the investigated treatment strategy. Insight into common HRQoL-problems can serve as a source of information for new patients and their loved ones. Despite the aforementioned challenges, incorporation of HRQoL as a clinical endpoint will provide evidence for the efficacy of a certain treatment on symptom relieve and improvement of HRQoL. The use of a DTF-specific measurement is encouraged as such as tool captures disease-specific problems. Final Remark The knowledge about desmoid-type fibromatosis (DTF) has grown significantly over the past decades and it continues to grow. Strengthened collaborations, accurate case registration, and the use of new technologies and representative tumour models will lay the foundation towards of a global consensus for the optimal treatment of this rare disease. Such a network will accumulate valuable insights, experiences and knowledge from all over the world and it will act as a powerful platform for health care providers committed to this rare disease. 12