Study Rationale and Background:
Metastatic cancer to the spine is a significant clinical challenge that can lead to severe pain, neurological compromise, and a diminished quality of life. Stereotactic Spine Radiosurgery (SSRS), also known as Stereotactic Ablative Radiotherapy (SABR), has emerged as a paradigm-shifting treatment. This advanced, non-invasive technique allows for the delivery of a single, highly ablative dose of radiation with unprecedented precision, which has shown excellent rates of pain control and tumor response while minimizing dose to the adjacent, critical spinal cord.
Despite the widespread adoption and promising results of SSRS, the optimal dose-fractionation schedule remains an area of active investigation. Previous research, including the landmark RTOG 0631 trial, has established single-fraction 16 Gy as an effective regimen. However, other evidence suggests that a higher radiation dose may lead to more durable local tumor control. This prospective, randomized phase II study, known as the SHINE trial, is designed to formally compare the efficacy and safety of a higher single-fraction dose against the current standard dose.
Study Design and Procedures:
This is a two-arm, parallel-group, randomized, open-label, multi-center study. After providing informed consent and confirming eligibility, participants will be randomly assigned on a 1:1 basis to receive either the standard dose or the high dose of SSRS. The randomization process will incorporate a minimization procedure to ensure balance between the two arms for the key prognostic factor of epidural or paraspinal tumor extension.
The core intervention for all participants is a single session of SSRS. The treatment will be meticulously planned using fused CT and MRI scans to accurately delineate the tumor (Gross Tumor Volume, GTV) and the area at potential microscopic risk (Clinical Target Volume, CTV), following international consensus guidelines from the International Spine Radiosurgery Consortium (ISRC). Radiation will be delivered using state-of-the-art techniques (IMRT or VMAT/RapidArc) with rigorous on-board image guidance to ensure accuracy. Strict dose constraints will be applied to protect the spinal cord and other nearby organs at risk.
Follow-up and Data Collection:
Following treatment, all participants will enter a comprehensive follow-up phase lasting up to two years. The schedule includes regular clinical evaluations, neurological assessments, and serial imaging (MRI and/or CT) to monitor treatment response and detect any potential late toxicities. Additionally, participants will complete validated questionnaires to assess changes in pain and health-related quality of life. Blood samples will be collected at baseline for correlative science studies to investigate potential genetic biomarkers (such as DDR2) and circulating factors that may predict treatment response or risk of skeletal side effects. This robust data collection will allow for a thorough comparison of the two treatment regimens.
