Nature and extent of the burden and risks associated with participation, benefit and group relatedness: Patients in the OPTIMAL cohort will perhaps not directly benefit from their participation. Participation will contribute to deriving patient-specific treatment modalities for future patients with bone metastases of the long bones. Risks associated with participation in the prospective cohort are considered negligible due to the observational nature of the study. The burden for the patients lies in completion of questionnaires, which is considered to be in proportion with the potential value of this research.