The role of stereotactic radiosurgery for prostate cancer spine metastasis - impact on hormone sensitivity and treatment outcomes: a systematic review of literature.

Spinal metastases are a common and morbid manifestation of advanced prostate cancer. Stereotactic body radiotherapy (SBRT), including single-fraction stereotactic radiosurgery (SRS), has emerged as a high-precision modality capable of delivering ablative doses with excellent local control. However, outcomes following spinal SBRT may differ according to hormonal sensitivity, particularly between hormone-sensitive prostate cancer (HSPC) and castration-resistant prostate cancer (CRPC). To systematically evaluate outcomes following stereotactic body radiotherapy for prostate cancer spinal metastases and assess differences between hormone-sensitive and castration-resistant disease. A systematic review was conducted in accordance with PRISMA guidelines. PubMed, Scopus, Web of Science, Cochrane Library, and Embase databases were searched on 20/06/2025. Eligible studies included adult patients with spinal metastases from prostate adenocarcinoma treated with SBRT/SRS and reported outcomes stratified by hormonal status where available. Data extracted included local control (LC), overall survival (OS), progression to castration resistance, pain response, treatment-related toxicity, and radiation dose-fractionation parameters including biologically effective dose (BED₃). Study quality was assessed using the ROBINS-I tool. Five studies including 322 patients and 501 spinal lesions were included. Spinal SBRT achieved high local control, with 1-2-year LC typically exceeding 90%. In the two studies (approximately 174 patients) that directly compared disease states, local control and survival were numerically and statistically more favourable in HSPC patients. Because this contrast rests on only two non-randomised studies with differing systemic-therapy exposure, it should be regarded as hypothesis-generating.Overall survival similarly favored HSPC, with 1- to 3-year OS rates markedly higher than those observed in CRPC populations. Progression to castration resistance was described in a minority of the studies but suggested more favorable disease control in HSPC patients, who also achieved deeper post-treatment PSA nadirs and lower rates of biochemical relapse. Pain response was favorable overall, with approximately half of symptomatic patients experiencing complete or partial pain relief. Treatment-related toxicity was low overall, with vertebral compression fracture rates ranging from 4-10% and predominantly grade I-II adverse events. Dose-fractionation schedules varied widely, with BED₃ values ranging from approximately 70 to 191 Gy₃; higher BED₃ regimens were commonly associated with durable local control, though optimal dosing thresholds remain undefined. These calculations are presented to illustrate radiobiological heterogeneity across treatment regimens, but they do not permit conclusions regarding dose-response relationships or optimal biological dose thresholds. Available data suggest that SBRT provides effective local control and meaningful symptom relief for spinal metastases from prostate cancer, with acceptable toxicity. Available data are consistent with more favourable outcomes in hormone-sensitive disease; however, because direct HSPC-versus-CRPC comparisons were available in only two of five studies, with non-randomised systemic-therapy allocation, this association should be considered hypothesis-generating and requires prospective confirmation. While SBRT represents an effective metastasis-directed therapy in both settings, the current evidence base is limited and derived from small retrospective and early prospective studies, thus prospective studies are needed to clarify optimal dosing strategies, BED-based thresholds, and the role of SBRT in modifying disease progression and survival, particularly in CRPC.