Bone density and fracture risk following SBRT for non-spine bone metastases
Yilin Cao, Gregory C. Stachelek, Wei Fu, Daniel Y. Song, Russell K. Hales, K. Ranh Voong, Jeffrey J. Meyer, Harry Quon, Chen Hu and Kristin J. Redmond
Purpose/methods: This retrospective study evaluated local recurrence (LR) and fracture risk in non-spine bone metastases treated with SBRT.
Results: 181 lesions in 116 patients are reported. The median dose was 27 Gy (range 15-40) in 3 fractions (range 1-6). The cumulative incidence of LR was 2.8%, 7.2% and 12.5% at 6 mo, 1 yr and 2 yrs. Fractures occurred in 11 lesions (6%). Radioresistant histology and increasing PTV predicted for LR on univariate analysis, while rib location was associated with control. Increasing PTV remained a significant predictor for LR on multivariate analysis. Univariate predictors of fracture risk included female gender, lytic lesions and poorer KPS. Average CT-approximated L1 trabecular attenuation in patients with fracture was significantly lower than in patients without fracture (112.2 vs. 142.6 Hounsfield units).
Conclusion: In the largest series to date, we report excellent local control for SBRT to non-spine bone metastases and a novel relationship between CT-based bone quality assessment and fracture risk.
Keywords: SBRT, non-spine bone, fracture