title: Spinal metastases: From conventional fractionated radiotherapy to single-dose SBRT.
abstract: OBJECTIVE
  To review the recent evolution of spine SBRT with emphasis on single dose treatments.
  
  
  BACKGROUND
  Radiation treatment of spine metastases represents a challenging problem in clinical oncology, because of the high risk of inflicting damage to the spinal cord. While conventional fractionated radiation therapy still constitutes the most commonly used modality for palliative treatment, notwithstanding its efficacy in terms of palliation of pain, local tumor control has been approximately 60%. This limited effectiveness is due to previous lack of technology to precisely target the tumor while avoiding the radiosensitive spinal cord, which constitutes a dose-limiting barrier to tumor cure.
  
  
  METHODS
  A thorough review of the available literature on spine SBRT has been carried out and critically assessed.
  
  
  RESULTS
  Stereotactic body radiotherapy (SBRT) emerges as an alternative, non-invasive high-precision approach, which allows escalation of tumor dose, while effectively sparing adjacent uninvolved organs at risk. Engaging technological advances, such as on-line Cone Beam Computed Tomography (CBCT), coupled with Dynamic Multi-Leaf Collimation (DMLC) and rapid intensity-modulated (IMRT) beam delivery, have promoted an interactive image-guided (IGRT) approach that precisely conforms treatment onto a defined target volume with a rapid dose fall-off to collateral non-target tissues, such as the spinal cord. Recent technological developments allow the use of the high-dose per fraction mode of hypofractionated SBRT for spinal oligometastatic cancer, even if only a few millimeters away from the tumor.
  
  
  CONCLUSIONS
  Single-dose spine SBRT, now increasingly implemented, yields unprecedented outcomes of local tumor ablation and safety, provided that advanced technology is employed.
authors.affiliation: Radiation Oncology, Champalimaud Centre for the Unknown, Lisbon, Portugal.
authors.forename: Carlo
authors.initials: C
authors.lastname: Greco
authors.affiliation: Radiation Oncology, Champalimaud Centre for the Unknown, Lisbon, Portugal.
authors.forename: Oriol
authors.initials: O
authors.lastname: Pares
authors.affiliation: Radiation Oncology, Champalimaud Centre for the Unknown, Lisbon, Portugal.
authors.forename: Nuno
authors.initials: N
authors.lastname: Pimentel
authors.affiliation: Radiation Oncology, Champalimaud Centre for the Unknown, Lisbon, Portugal.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Moser
authors.affiliation: Radiation Oncology, Champalimaud Centre for the Unknown, Lisbon, Portugal.
authors.forename: Vasco
authors.initials: V
authors.lastname: Louro
authors.affiliation: Radiation Oncology, Champalimaud Centre for the Unknown, Lisbon, Portugal.
authors.forename: Xavier
authors.initials: X
authors.lastname: Morales
authors.affiliation: Radiation Oncology, Champalimaud Centre for the Unknown, Lisbon, Portugal.
authors.forename: Barbara
authors.initials: B
authors.lastname: Salas
authors.affiliation: Radiation Oncology, Champalimaud Centre for the Unknown, Lisbon, Portugal.
authors.forename: Zvi
authors.initials: Z
authors.lastname: Fuks
keywords: IGRT; Radiosurgery; SBRT; SRS; Single-fraction; Stereotactic radiotherapy