Stability and survival analysis of elderly patients with osteolytic spinal bone metastases after palliative radiotherapy Results from a large multicenter cohort

Purpose This retrospective study aimed to evaluate the stability and fracture rates of osteolytic spinal bone metastases (SBM) in elderly patients following palliative radiotherapy (RT) and to derive prognostic factors for stability and survival. Methods A total of 322 patients aged at least 70 years received palliative RT at two major German academic medical centers or at the German Cancer Research Center. Stability assessment was based on the validated Taneichi score prior to RT and at 3 and 6 months after RT. The survival time following RT was assessed, and prognostic factors for stability and survival were analyzed. Results Prior to RT, 183 patients (57%) exhibited unstable SBM and 68 patients (21%) pathological fractures. At 3 and 6 months after RT, significant recalcification and stabilization were evident in 19% (23/118) and 40% (31/78) of surviving patients, respectively. Only 17 patients (5%) experienced new pathological fractures following RT. Tumor histology was found to significantly influence stabilization rates with only breast cancer patients exhibiting increased stabilization compared to patients with other histologies. The median survival time and 6-month survival rates following RT were 5.4 months (95% confidence interval 4.4-7.2 months) and 48%, respectively. The patients' performance status was found to be the strongest predictor for survival after RT in this patient cohort; further factors demonstrating a significant association with survival were the application of systemic treatment, the number of SBM and the primary tumor histology. To analyze the influence of age on survival after RT, study patients were stratified into 3 age groups (i.e., 70-74 years, 75-79 years, and >= 80 years). The subgroup of patients aged at least 80 years showed a strong trend towards a worse survival time following RT compared to younger patients (i.e., 6-month survival rate 39% vs. 51%; p= 0.06, log-rank test). Conclusions Prognostic factors influencing overall survival such as performance status and histology should guide the choice for palliative RT for SBM. Strongly hypofractionated RT regimes may be advisable for most elderly patients considering the overall poor prognosis in order to reduce hospitalization times.