This study evaluates a new radiation treatment approach for patients with cancer that has spread to the spine (vertebral metastases) and involves limited extension around the spinal cord without causing compression (non-compressive epiduritis). This condition is common and can lead to serious complications, including pain and spinal cord compression, potentially affecting mobility and quality of life.

The current standard of care is conventional radiotherapy, which is effective for symptom relief but may provide limited long-term tumor control. As advances in cancer treatments have improved survival, there is an increasing need for treatment approaches that better prevent local tumor progression in the spine.

This randomized clinical trial compares standard radiotherapy with stereotactic radiotherapy (SRT), an advanced and highly precise radiation technique that delivers higher doses directly to the tumor while minimizing exposure to surrounding healthy tissues, including the spinal cord.

The primary objective is to determine whether SRT can improve local disease control while maintaining an acceptable safety profile. The study will evaluate the proportion of patients who are alive without spinal disease progression (including spinal cord compression or local tumor recurrence) at one year after treatment. Secondary outcomes include treatment-related side effects, time to disease progression, overall survival, quality of life, feasibility of delivering SRT within a defined timeframe, risk of vertebral fractures, and need for additional radiation treatment.

Eligible patients will have an estimated life expectancy greater than six months. Strict radiation dose constraints will be applied to minimize the risk of spinal cord injury, and patient safety will be closely monitored, including implementation of an early stopping rule in case of unexpected severe toxicity.

The hypothesis of the study is that stereotactic radiotherapy will improve local control of spinal metastases compared with standard radiotherapy, without increasing the risk of serious adverse effects.

Inclusion Criteria:

• Histologically confirmed solid tumor;
• Vertebral bone metastasis located between C2 and S1 (inclusive) with epiduritis (spinal cord or cauda equina) without clinical and/or radiological spinal cord compression on MRI;
• Performance status (PS) ≤ 1;
• Spinal Instability Neoplastic Score (SINS) ≤12;
• Patient has been informed and has provided freely given, written, and signed informed consent;
• Patient is affiliated with or a beneficiary of the national health insurance system.

Exclusion Criteria:

• Neurological deficit attributable to spinal cord compression or cauda equina syndrome;
• Patient experiencing pain that prevents lying down for 30 minutes despite optimal analgesic treatment;
• Life expectancy ≤6 months as estimated by the investigator;
• Neurosurgical indication (preventive or decompressive) prior to radiotherapy;
• More than one epiduritis lesion requiring treatment;
• Prior surgery on the same vertebra targeted in the protocol;
• Epiduritis and/or bone lesion extending over more than three contiguous vertebral levels;
• Previous irradiation of the spine with cumulative dose with cumulative spinal cord dose EQD2 >50 Gy, α/β = 2;
• Contraindication to MRI;
• Pregnant or breastfeeding woman;
• Patient under legal protection, guardianship, or unable to provide informed consent;
• Inability to comply with study follow-up due to geographic, social, or psychological reasons.