A Prospective Randomized Clinical Trial of Single Versus Multiple Fractionated Stereotactic Spine Radiosurgery for Patients With Spinal Metastases

Although conventionally fractionated radiation therapy has been utilized for decades, the rates of complete pain relief and local control for complex tumors are sub-optimal. The management of patients with spine metastasis has undergone a great deal of change in the past 5 years. Improvements in neuroimaging, computer-assisted treatment planning, and radiation therapy techniques have led to the development of extracranial radiosurgery.

SSRS is rapidly being adopted in the clinic as preliminary applications of SSRS appears promising. However, the role of SSRS remains in its infancy and lacked high-quality evidence about the treatment schedule and lacked a solid understanding of the adverse events. The Radiation Therapy Oncology Group (RTOG) 0631 phase 2/3 study was initiated to determine whether a more intensive radiation dose delivered by image guided 16-Gy dose single fraction SRS could improve pain control and quality of life as compared with conventional external-beam radiotherapy in patients with localized spine metastases . While other group used treatment schedule in a total dose of 27-30 Gy in three fractions.

Serious adverse events such as vertebral compression fracture (VCF) is a fairly low-risk adverse event after conventional radiotherapy, nevertheless, the crude risk estimates for VCF after spinal stereotactic body radiation therapy is relative more frequent. Previous reports has raised the caution about the given dose and predictive factors, however; whether these two most widely used SSRS schedule (ie. single fraction versus three fractions) provide equivalent pain control and minimal side effects remained to be answered.

There was no randomized trials to assess the SSRS treatment response and SSRS induced grade 3 or higher adverse events between the two most widely adopted scheme. Thus, the investigators proposed the randomized study to determine the feasibility of delivering a single 16-Gy SRS dose versus 3 fractions 24-Gy SRS dose and tried to evaluate the toxicity profile and gain robust data as well as predictive factors regarding the risk of complications after SSRS, including VCF. The investigators will incorporate the recently developed and reported reliable Spinal Instability Neoplastic Scoring (SINS) system and well-designed patient reported outcome measures (PROMs) into the protocol to predict the adverse event and quality of life of each participant. The researchers also tried to investigate the possible associations of the potential bone biomarkers for the risk assessment of SSRS-related adverse bone events.

Since the patients were randomized for treatment arms, the effectiveness of SSRS treatment scheme and adverse profile can be investigated more properly in the present study.