The primary goal of the study is to determine the local control-rate after radiotherapy (RT) with and without simultaneous integrated boost (SIB) concepts in patients with bone metastases of the spine. Further study objectives are survival, and clinical parameters such as pain, quality of life (QoL) and fatigue. We expect an improvement in local control and consecutively an increased re-sclerotization of the bone metastasis due to a higher biological dose in the tumor area. Therefore patients could benefit in quality-of-life, pain relief and mobility.

The vertebral column is the main localization of bone metastases and is where they frequently indicate an advanced stage of a malignant primary disease [1, 2]. Two thirds of all patients with tumors are estimated to develop bone metastases in the course of their disease [3]. Spinal bone metastases are of central impact for patients in a palliative setting. The clinical symptoms include pain at rest and under exercise but also impaired activity of daily life, the risk of pathological fractures, and neurological deficits. Local control is the essential factor for stability of the vertebral body of patients with spinal bone metastases. In regard to re-calcification of former osteolytic lesions, palliative radiotherapy (RT) represents an effective treatment option [4]. The most common schedule was specified as 30 Gy in 10 fractions. Stereotactic body radiation therapy (SBRT) using intensity-modulated radiotherapy (IMRT) can be a safe modality for treating spinal metastasis with enhanced targeting accuracy [5]. Secondly, IMRT to the spine was well tolerated (especially in the spinal cord), had no significant late toxicities, and spared other organs at risk simultaneously [6]. The main problem of the standard schedule is the limited dose application to the metastasis due to organ at risk myelon. Therefore, the aims of this study is to apply a high biological dose in the tumor region and to achieve an improved result related to local control for palliative patients with painful spinal bone metastases. Secondly, the aim is to evaluate QoL, fatigue, and survival of three different RT-techniques. To the best of our knowledge, no comparable randomized study has been described in the literature so far.

Inclusion Criteria:

• Patients with a histologically confirmed tumor diagnosis, with secondarily diagnosed solitary/multiple metastatic spinal bone metastases
• Indication for RT of the bone metastasis
• Age: between 18 and 80 years
• Karnofsky performance score ≥ 70
• Signed Declaration of Informed Consent
• Bisphosphonate therapy

Exclusion Criteria:

• Significant neurological or psychiatric disorders, including dementia and epileptic seizures
• Lacking or diminished legal capacity
• foregoing radiotherapy in the planned RT area
• Any medical of psychological condition that the study director considers a preventive factor for the patient's ability to complete the study or to adequately understand the scope of the study and to give his/her consent