The goal of this clinical trial is to assess the impact of reducing the volume of palliative metastatic bone irradiation on analgesic effectiveness at day 30 and to evaluate the efficiency of telemonitoring in identifying patients who could benefit from Patient-Reported Outcomes (PROs) and require care.

These objectives will be addressed in a multicenter, randomized, prospective study with two arms:

A standard arm with spinal irradiation without sparing the adjacent vertebrae. An experimental arm with spinal irradiation sparing the adjacent vertebrae. The results will determine whether reducing the irradiated volume can maintain effective pain relief while minimizing side effects.

Palliative analgesic radiotherapy (RT) is used to relieve pain in patients with bone metastases. This technique involves irradiating the vertebrae above and below the ones responsible for the pain. Traditional two-dimensional radiotherapy (2D-RT) was characterized by a physical penumbra that could extend up to 50% of a vertebra's height, leading to underdosing of the target volume and, consequently, reduced analgesic effectiveness.

However, computed tomography (CT) scans or CT-based imaging have replaced these practices, allowing for high precision in delineating target volumes. Despite advancements in irradiation techniques, the physical penumbra is now negligible with modern machines, reducing the need for large margins and thereby limiting side effects associated with the irradiation of healthy tissues.

These factors have led us to conduct a clinical trial to assess the impact of reducing the volume of palliative metastatic bone irradiation on analgesic effectiveness at day 30 (D30) and to evaluate the efficiency of telemonitoring in identifying patients who could benefit from Patient-PROs and require care.

These objectives will be pursued in a multicenter, randomized, prospective study with two arms:

A standard arm, with spinal irradiation without sparing the adjacent vertebrae. An experimental arm, with spinal irradiation sparing the adjacent vertebrae. The results will determine whether reducing the irradiated volume can maintain effective pain relief while minimizing side effects. This could lead to changes in current palliative radiotherapy practices, reduce toxicity risks, and improve patients' quality of life.

Inclusion Criteria:

• Patient with bone pain related to at least 1 or more bone metastases of spinal location, contiguous or not, cervical (excluding C1), thoracic, lumbar or sacral up to and including S2; a patient can be included even if he or she is irradiated concomitantly or not for analgesic purposes on another non-spinal bone metastatic site. Bone lesions are objective on an imaging examination less than 3 months old: CT and/or MRI and/or PET and/or bone scintigraphy;
• Patient with at least moderate pain with EN ≥ 5;
• Patient on analgesic drug treatment for at least 7 days or poor tolerance of analgesics;
• Patient irradiated for palliative analgesic purposes. Post-cementoplasty irradiation is possible; an extension to the soft tissues is not a contraindication to inclusion;
• Patient with a validated palliative bone irradiation plan: 8 Gy / 1 fr or 20 Gy / 5 fr;
• Patient with planning only in static IMRT, arc therapy or helical tomotherapy;
• Patient with a primary cancer or a haemopathy;
• Patient currently undergoing or not a specific oncological systemic treatment, left to the discretion of the investigating physician;
• Patient currently undergoing or not a treatment with bisphosphonates and denosumab, left to the discretion of the investigating physician;
• WHO ≤ 2;
• Patient with a life expectancy ≥ 3 months;
• Patient able and agreeing to follow all study procedures in accordance with the protocol;
• Patient having understood, signed and dated the consent form;
• Patient affiliated to the social security system.

Exclusion Criteria:

• Pediatric patient;
• Patient undergoing stereotaxic irradiation;
• Patient undergoing oligometastatic disease;
• Patient undergoing re-irradiation unless the dose is not limiting to OARs;
• Patient treated with RT2D (conventional 2-dimensional radiotherapy) or RT3D (conventional 3-dimensional radiotherapy);
• Patient with MESCC (metastatic epidural spinal cord compression) except for a Bilsky grade < 1b;
• Patient who does not have a means of responding to online questionnaires;
• Patient and their entourage who cannot read or express themselves in French;
• Visually impaired patient;
• Patient already included in another therapeutic trial with an experimental molecule;
• Persons deprived of liberty or under guardianship (including curatorship).
• Pregnant woman, likely to be pregnant, or breastfeeding