The Prognostic Impact of the Ki-67 Proliferation Index in Patients with Surgically Treated Spinal Metastases

The prognostic assessment of patients with spinal metastases is primarily based on clinical and radiological parameters. Biological tumor characteristics such as the proliferation marker Ki-67 have prognostic relevance in various metastatic settings. This study aimed to evaluate the prognostic impact of the Ki-67 proliferation index on survival outcomes in patients undergoing surgery for spinal metastases.

We included 166 patients who underwent surgical treatment for spinal metastases at our university clinic between 2015 and 2024. Clinical, functional, tumor-related, and perioperative variables were collected. Receiver operating characteristic (ROC) analysis was performed to evaluate the discriminatory ability of Ki-67, and comparisons were made between patient groups according to Ki-67 expression (≤20% vs. >20%).

Based on ROC analysis, Ki-67 demonstrated a moderate but significant predictive ability for 1-year mortality (area under the curve [AUC]: 0.69, p = 0.001). Patients with a Ki-67 index of >20% showed a significantly shorter overall survival than those with a lower Ki-67 index of ≤20% (median overall survival: 5.0 vs. 14.5 months, p < 0.001). One-year mortality was significantly higher in the high Ki-67 group (78.9% vs. 41.8%, p = 0.001). High Ki-67 expression was associated with more aggressive tumor characteristics but was not associated with increased perioperative morbidity.

The Ki-67 proliferation index is a significant prognostic biomarker in surgically treated patients with spinal metastases. A Ki-67 index threshold of 20% identifies patients at increased risk of early mortality and significantly reduced overall survival.