Stereotactic Body Radiotherapy Followed by Surgical Stabilization for Patients With Unstable Spinal Metastases: Cohort Study According to the IDEAL Recommendations

Rationale Sixty-five percent of cancer patients with terminal illness have bone metastases, with debilitating pain often as the severe consequence. The spine is the most common location for bone metastases. Standard treatment of unstable vertebral metastases consists of stabilizing surgery, followed by external beam radiotherapy after two weeks. Although this approach is effective in 60-70% of patients, it is has several downsides. Firstly, because of the two weeks interval between surgery and external beam radiotherapy, necessary for sufficient wound healing, it takes time before radiotherapy-induced pain relief is achieved. Moreover, the surgical implants used cause scatter artifacts on planning computed tomography images which prohibits high-resolution imaging and accurate targeting of the lesion. Multiple hospital visits (ranging from 1 to 10) are needed for administration of external beam irradiation, and in about 30-40% of patients no adequate pain response is achieved. An alternative treatment strategy, which would lead to faster pain relief in a higher proportion of patients with less hospital visits, would be highly desirable from the patient's perspective. Secondly, this strategy delays the start of systemic therapy.

Objective The main outcome of this study is pain response 4 weeks after start of the treatment.

Study design Prospective cohort study nested within the PRESENT cohort being a phase 2b study according to the IDEAL recommendations

Study population All patients, male and female, with impending spinal instability requiring surgical intervention and radiotherapy at the University Medical Center Utrecht

Intervention The combined treatment of stereotactic body radiotherapy and pedicle screw fixation in a 24 to 48-hour window for the treatment of painful unstable metastases of the cervical, thoracic and/or lumbar spine.