Prognostic Factors Associated with Survival in Patients with Symptomatic Spinal Bone Metastases: a Retrospective Cohort Study of 1,043 Patients

Background: Expected survival is a major factor influencing extent of treatment for symptomatic spinal bone metastases (SBM). Predictive models have been developed, but their use can lead to over- or undertreatment.. The study objective was to identify prognostic factors associated with survival in patients with symptomatic SBM and to create a validated risk stratification model.

Methods: All patients who were treated for symptomatic SBM between 2001 and 2010 were included in this single center retrospective study. Medical records were reviewed for type of primary cancer, performance status, presence of visceral, brain and bone metastases, number and location of spinal metastases, and neurological functioning. Performance status was assessed with the Karnofsky performance score and neurological functioning with the Frankel scale. Analysis was performed using Kaplan-Meier curves, univariate log-rank tests, Cox regression models, and Harrell's C statistic.

Results: A total of 1 043 patients were studied. The most prevalent tumors were those of breast (n = 299), lung (n = 250), and prostate (n = 215). Median follow-up duration was 6.6 years, and 6 patients were lost to follow-up. Based on the results of the uni- and multivariate analyses, 4 categories were created. Median survival in category A was 31.2 months (95% CI, 25.2-37.3 months), 15.4 months (95% CI, 11.9-18.2 months) for category B, 4.8 months (95% CI, 4.1-5.4 months) for category C, and 1.6 months (95% CI, 1.4-1.9 months) for category D. Harrell's C statistic was calculated after the model was applied to an external dataset, yielding a result of 0.69.

Conclusion: Assessing patients according to the presented model results in 4 categories with significantly different survival times.