Outcomes of Spinal Metastases Based on Primary Tumors: A Systematic Review and Meta-analysis

Introduction: Spinal metastasis (SM) is an important topic in spinal oncology due to its relatively high cumulative incidence and very poor prognosis. However, little is known about patient outcomes of SM based on the primary cancer type. This study aimed to systematically review the current literature on SM by primary cancer type and meta-analyze patient outcomes, focusing on recurrence, 1-year survival, and 2-year survival.

Methods: We conducted a systematic literature search in the databases Embase, Medline, Scopus, Web of Science, and Cochrane Central from inception to 01/21/2024. We included studies that reported outcomes in patients with SM from any primary cancer. We then qualitatively described the results and performed random-effects meta-analyses. The quality assessment of included studies was conducted using ROBINS I.

Results: All results are given as pooled proportions. For breast cancer SM, recurrence was 0.044 [95% CI: 0.006; 0.272], 1-year survival was 0.678 [95% CI: 0.569; 0.770], and 2-year survival was 0.429 [95% CI: 0.238; 0.644]. For lung cancer SM, recurrence was 0.087 [95% CI: 0.058; 0.129], 1-year survival was 0.357 [95% CI: 0.224; 0.517], and 2-year survival was 0.205 [95% CI: 0.081; 0.429]. For prostate cancer SM, 1-year survival was 0.695 [95% CI: 0.516; 0.829]. For renal cancer SM, recurrence was 0.085 [95% CI: 0.037; 0.183], 1-year survival was 0.512 [95% CI: 0.376; 0.646], and 2-year survival was 0.313 [95% CI: 0.231; 0.409].

Conclusion : Lung cancer SM had the worst outcomes across all three outcomes of interest. Breast cancer SM had the best outcomes for recurrence and 2-year survival, and prostate cancer SM had the highest 1-year survival rate. Our results, combined with the corresponding prognoses of different primary cancers, can potentially inform treatment decisions. Further research should investigate what factors promote SM from various primary cancer types, as this could improve our understanding of treatment targets that reduce the risk of SM.