Stereotactic Body Radiosurgery for Spinal Metastatic Disease: An Evidence-Based Review

Abstract

Spinal metastasis is a problem that afflicts many cancer patients. Traditionally, conventional fractionated radiation therapy and/or surgery have been the most common approaches for managing such patients. Through technical advances in radiotherapy, high dose radiation with extremely steep drop off can now be delivered to a limited target volume along the spine under image-guidance with very high precision. This procedure, known as stereotactic body radiosurgery, provides a technique to rapidly treat selected spinal metastasis patients with single- or limited-fraction treatments that have similar to superior efficacies compared with more established approaches. This review describes current treatment systems in use to deliver stereotactic body radiosurgery as well as results of some of the larger case series from a number of institutions that report outcomes of patients treated for spinal metastatic disease. These series include nearly 1400 patients and report a cumulative local control rate of 90% with myelopathy risk that is significantly less than 1%. Based on this comprehensive review of the literature, we believe that stereotactic body radiosurgery is an established treatment modality for patients with spinal metastatic disease that is both safe and highly effective.

Spinal metastases: From conventional fractionated radiotherapy to single-dose SBRT

“…A recent pooled analysis of published series using both single fraction at various dose levels and multi-fraction regimens (up to 5 sessions) entailed 1775 lesions in 1388 patients. 19 Followup was mostly short-termed (<18 months in 12/15 studies) yielding an overall local control rate of 90% and a risk of radiation myelopathy of 0.4%, with no apparent differences in early outcomes between single dose and 3-5 fraction of SBRT. Prospective randomized trials are few and largely still underway.…”

Stereotactic Body Radiation Therapy: A Review of Applications and Outcomes

“…This allows the system to automatically compare this marker information with reference information to move the treatment couch to the desired position [20]. Gill et al commenting on local control and toxicity of SBRT of single vertebrae spinal tumors reported that a doses of [30][31][32][33][34][35] Gy were given via Cyberknife technology, and at 34 months median follow-up (IQR, 25-40 months) for surviving patients, the 1-and 2-year Kaplan-Meier local control estimates were 80 and 73%, respectively [21]. In effect, SBRT for primary or metastatic spinal column cancers is a noninvasive procedure with excellent control rates that is being widely adopted by radiation oncologists across the United States.…”

“…Also, when the number of beams used is sufficiently high, the choice of beam direction becomes less significant [2]. Recent developments in volumetric modulated arc techniques have the potential to create conformal dose distributions, achieve the required level of normal tissue sparing, and reduce treatment times, as compared to their static field counterparts [33].…”

“…Bibault et al reported successful treatment of hepatocellular carcinoma with a median total dose of 45 Gy given in three mean fractions of 15 Gy. Tumors treated had a median diameter of 37 mm with CTVs 10 mm larger in all directions than the gross tumor volume and the PTV was 1.5 mm [33]. While analysing the shifts of lung tumors during respiration Krimski et al reported that anterior/posterior shifts of tumors were about 1 mm on average while cranial/caudal shifts averaged about 2 mm and that the precision of SBRT was sufficient to cover tumor ablation while minimizing normal tissue to radiation exposure [35].…”

Stereotactic radiosurgery (SRS) and stereotactic radiation therapy (SRT) for neurooncological and neurological diseases: state of the art and future perspectives

“…In neurooncology, spinal metastases are of major interest. A current evidence-based review of Hall et al reviewed 1388 patients with 1775 lesions treated with stereotactic body radiosurgery [19]. Over 50% of these patients received radiosurgery as a second course of radiotherapy.…”