Two-thirds of all cancer patients develop bone metastases during the course of their disease [
1]. This form of distant relapse occurs from many types of solid cancers, especially from lung, breast, and prostate [
2]. Bone involvement can also be extensive in certain hematologic malignancies [
3,
4]. About 30% of all skeletal metastases and 10% of all primary bone tumors are located in the spinal column [
5], mostly the lumbar (52%), thoracic (36%), and cervical (12%) spine [
6]. The exact mechanism of bone metastasis is not fully understood. It is postulated that bone metastases arise as a detachment of tumor cells from the primary tumor and reach the bone by intravascular penetration, resulting in adhesion in distinct bone areas. The tumor cells cause local changes of the bone structure, caused by an imbalance of bone remodeling. Bone metastases present as osteoplastic, osteolytic, or mixed osteolytic/osteoplastic tumor masses. Many metastatic bone lesions cause few or no symptoms, but for skeletal-related events, pain is the most common symptom; many patients with bone metastasis experience significant pain at some point during their disease course [
7]. Other skeletal-related events include reduce activity in daily life (ADL), decreased energy, hypercalcemia, and risk of pathological fractures and neurological deficits. Pathologic bone fractures occur in 5% and spinal cord compression in 10–15% [
5]. Restrictions of movement of the spinal column may have a devastating long-term impact on function, mobility, independence, health, and quality of life (QoL). External beam radiotherapy has an established role in the management of patients with bone metastases of the spine. The fractionation schedule applying 30 Gray in ten fractions is a safe and effective treatment modality commonly used to achieve palliation of pain associated with spinal metastases [
8]. In about 50–80% of the patients, a decrease of pain is reported and about 30% of the patients showed complete remission of pain [
8]. Stereotactic body radiation therapy (SBRT) using intensity-modulated radiotherapy (IMRT) can be a safe treatment option for treating spinal metastasis with enhanced targeting accuracy [
9,
10]. Published data report that IMRT to the spine was well tolerated, had no significant late toxicities, and spared other organs at risk [
11]. Pre-treatment megavoltage computed tomography (CT) allows for the control of the patient position and improves treatment accuracy [
12].
This study aims at evaluating therapeutic outcomes in terms of local control through a higher biological dose in the tumor area by using SIB-IMRT and to test shortened fractionation schedules in palliative patients. Toxicity, fatigue, and QoL improvements will be evaluated. To the best of our knowledge, no comparable randomized study has been described in the literature so far.