A study published in the Journal of Neurosurgery: Spine indicates that both single-session and multiple-session stereotactic radiosurgeries are effective for the treatment of spinal metastases.
Dwight Heron, Department of Radiation Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, USA, and co-authors report in their study that support for stereotactic radiosurgery for the management of spinal metastases, either as primary palliative therapy or as salvage therapy after failure prior radiation therapy or surgery, has grown because of the limitations of external beam radiation therapy. They wrote: “Stereotactic radiosurgery can deliver a highly conformal, large radiation dose to a localised tumour while sparing the adjacent spinal cord [unlike external beam radiotherapy], thereby reducing the risk of radiation-induced myelitis.”
However, at present, the ideal dose and other treatment parameters of stereotactic radiosurgery has not yet been defined. Thus, in their study, Heron et al compared multiple-session stereotactic radiosurgery with single-session stereotactic radiosurgery (using the CyberKnife system, Accuray).
In the retrospective review, 104 patients underwent multiple-session stereotactic radiosrugery and 124 patients underwent single-session sterotactic radiosurgery. Patients were included in the study if they had at least one spinal metastatic lesion (at any level) and did or did not have a history of prior radiation therapy or surgery for the same lesion, but excluded if they had spinal instability, life expectancy of less than three months, or frank cord compression.
There was not a statistical difference between the two approaches in the amount of pain relief delivered to the patients (defined as a long-term decrease in pain; 73% for multiple-session vs. 71% for single-session; p=0.617), but the single-session approach (mean dose 16.3Gy; range 6–20Gy) was associated with significantly more pain control (percentage of patients with pain relief or pain stabilisation) than the multiple-session approach (100% vs. 88%, respectively; p=0.003). However, the multiple-session approach (mean dose 20.6Gy in three fractions [range 9–26.3Gy], 23.8Gy in four fractions [16–18Gy], and 24.5Gy in five fractions [15–35Gy]) was associated with greater tumour control probability (96% vs. 70%; p=0.001), greater overall survival (63% vs. 46%; p=0.002), and less need for re-treatment (1% vs. 13%; p<0.001) than the single-session approach. The two approaches were not statistically different in terms of improvement in neurological status or rate of complications.
Heron et al concluded: “Single-session and multiple-session stereotactic radiosurgery are safe and effective in treating spinal metastases.”