Stereotactic radiotherapy for rib metastases from prostate cancer: A multicenter real-world analysis of local control, pain response, and treatment tolerance (RIBRISK)
- Author(s)
- Bilski, M; Mastroleo, F; Banaszek, I; Korab, K; Kuźnicki, W; Jędrzejczak, N; Peszyńska-Piorun, M; Ponikowska, J; Fijuth, J; Jereczek Fossa, BA; Zilli, T; Kotecha, R; Siva, S; Guckenberger, M; Kishan, A; Kuncman, Ł;
- Journal Title
- Therapeutic Advances in Medical Oncology
- Publication Type
- Research article
- Abstract
- BACKGROUND: Stereotactic body radiotherapy (SBRT) is increasingly used for patients with oligometastatic prostate cancer, yet the optimal target definition, dose, and toxicity profile for rib metastases remain uncertain. OBJECTIVES: We assessed local control (LC), toxicity, and the risk of radiation-induced rib fracture (RF) after SBRT for rib metastases. DESIGN: Retrospective multicenter cohort study. METHODS: We analyzed prostate cancer patients with radiologically diagnosed rib metastases treated with SBRT and >=12 months of follow-up. Outcomes were descriptively compared between gross tumor volume (GTV)-only and GTV plus an intraosseous clinical target volume (CTV) margin. Analyses included Kaplan-Meier survival estimates, cumulative incidence functions, and exploratory univariable Cox and logistic regression; no formal equivalence testing or multivariable validation was attempted because event numbers were very low. RESULTS: We included 102 patients with a median follow-up of 20 months. The 1- and 2-year LC rates were 97.9% and 96.3%, respectively. At 3 years, local progression was 2.1% in the GTV-only group, absent in patients treated with >=10 mm margins, and numerically highest with 3-5 mm CTV margins (13.5%, p=0.022). Among 13 symptomatic patients, pain control was excellent, with complete or partial response in all patients within 6 months. No grade >=3 toxicities occurred. RFs were rare (n=3, 2.9%), comprising one symptomatic Grade 2 event (0.9%) and two asymptomatic Grade 1 events (2.0%). Baseline symptoms and extraosseous infiltration were associated with RF in exploratory univariable analysis, but confidence intervals were wide. Higher PTV dose exposure, particularly PTV D50% (36.9 vs. 31.1 Gy, p=0.041), was also observed among RF cases. CONCLUSIONS: SBRT for rib metastases from prostate cancer was associated with high LC, pain relief, and low observed toxicity in this retrospective real-world cohort. GTV-only contouring may be feasible in carefully selected patients staged and planned with PSMA-PET/CT, but the non-randomized design, baseline imbalances, short follow-up, and very low event count preclude drawing conclusions about equivalence or independent validation. RF predictor analyses should be considered exploratory and hypothesis-generating.; Rib metastases are a common site of bone spread in prostate cancer, but there is limited rib-specific evidence on stereotactic body radiotherapy (SBRT). In this retrospective multicenter study, SBRT for prostate cancer rib metastases was associated with high observed local control, pain improvement, and low observed severe toxicity during the available follow-up. Radiation-induced rib fractures were uncommon: one patient had a symptomatic Grade 2 fracture, while two Grade 1 fractures were asymptomatic radiographic findings. The study also explored whether treating only the visible tumor volume could be considered in selected patients planned with modern imaging such as PSMA-PET/CT. Because the study was retrospective, the treatment groups were imbalanced, follow-up was limited for late toxicity, and event numbers were very low; these findings do not prove that GTV-only contouring is equivalent to using a clinical target volume margin. Larger prospective studies with longer follow-up are needed, particularly to define late rib fracture and chest wall toxicity.; eng
- Publisher
- Sage
- Keywords
- Sabr; Sbrt; chest wall toxicity; contouring; metastasis-directed therapy; oligometastatic disease; prostate cancer; radiation-induced rib fracture; rib metastases; stereotactic body radiotherapy
- Department(s)
- Radiation Oncology
- Publisher's Version
- https://doi.org/10.1177/17588359261476045
- Open Access at Publisher's Site
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Creation Date: 2026-09-03 12:44:09
Last Modified: 2026-09-03 12:44:21