Changes of Bone Strength Evaluated by CT-based Finite Element Methods in Radiotherapy for Bone Metastases of the Proximal Femur

Abstract

univariate analysis, Cox proportional hazards regression for multivariate analysis. Results: Since 2014, 127 patients were identified who met the inclusion criteria, 44% female, 56% male, median age 62. 70 received SBRT, 57 SRS. 80% of patients were treated for lung cancer, 20% other primary sites. 53% of patients received nivolumab, 29% pembrolizumab, 13% atezolizumab, 5% other. 20% received immunotherapy before SBRT/SRS, 39% during SBRT/SRS, 41% after. 86 patients had died by the time of analysis, the median OS for the whole cohort was 9.7 months. Patients who had completed immunotherapy prior to SBRT/SRS had worse OS than those who received concurrent therapy or immunotherapy after SBRT/ SRS, with a difference in median OS of 3.6 months versus 13.0 months (p Z 0.010), this was retained on multivariate analysis (p Z 0.011). There was no significant difference in OS between patients receiving SRS versus SBRT (p Z 0.30, 0.21), gender (p Z 0.43, 0.60), age >62 (p Z 0.73, 0.84), or lung primary vs. others (p Z 0.89, 0.41) on univariate or multivariate analysis. Conclusion: Overall survival appears to be worse in patients who complete immunotherapy prior to SBRT/SRS compared to those receiving it concurrently or after. The design of this retrospective review may be prone to lead-time bias, although the difference in median survival is longer than the 6-month window before SBRT/SRS and could only account for part of this difference. Further analysis into causes of death and toxicity as well as prospective studies are needed to confirm the results of this analysis.