Palliative radiotherapy is an effective treatment for patients with painful bone metastases. Standard workflows often involve long waiting times or multiple visits. Fast palliation completed during a single clinic visit can be achieved by omitting a planning CT scan, and using available diagnostic imaging for treatment planning. The adaptive treatment platforms provides the possibility to adapt positions differences between the diagnostic CT and radiotherapy treatment of the target and organs at risk. In this study, the investigators will investigate the experiences of patients who have been treated with this fast-adaptive workflow (FAST-METS) using 2 questionnaires.

Palliative radiotherapy is an effective treatment for patients with painful bone metastases, and currently the investigators have clinically implemented the FAST-METS procedure at the department. All patients referred for palliative radiotherapy, in whom diagnostic imaging performed within 4 weeks is available, are eligible for this adaptive workflow. Consultation by telephone is done beforehand to verify whether the complaints correspond to the location of the metastasis.

This single-institutional, explorative study will investigate the experiences and quality of life of patients who were treated with this workflow. Two study questionnaires are used, and informed consent will be obtained for both. The EQ-5D-5L questionnaire will be completed on the day of treatment, after 6 weeks and 3 months post-treatment. The other questionnaire used was developed for patients treated with adaptive radiotherapy. Two patients groups will be studied, namely those undergoing simple and complex palliative radiotherapy. Patients treated with complex palliative radiotherapy are defined as those referred for re-irradiation to the site of metastasis, patients undergoing concurrent systemic therapy, and patients treated with a single fraction radiation dose exceeding 8 Gy.

In addition, the study will evaluate time spent on treatment preparation and delivery proces, and dosimetric aspects of the treatment.

Inclusion Criteria:

• Patients referred for palliative radiotherapy to metastases
• Recent diagnostic CT scan (preferably <4 weeks) of the metastasis with full body contour of the patient included.

Exclusion Criteria:

• A solitairy metastasis from a primairy tumor with good a prognosis
• A metastasis located in ventral ribs where respiratory motion of the target is expected
• Patients who are not fluent in Dutch

Patients referred for palliative radiotherapy, in whom diagnostic imaging performed in the preceding 4 weeks is available.