Prognostic Differences in Patients with Solitary and Multiple Spinal Metastases

To investigate the association between the number of metastases to the spine and survival in patients with metastatic spinal cord compression (MSCC), as well as the prognosis difference between patients with solitary spinal metastasis (SSM) and multiple spinal metastases (MSM).

Three institutional databases were searched to identify all patients who had undergone spinal surgery for metastatic spinal tumors between March 2002 and June 2010. As well as age and gender, preoperative medical conditions were collected from medical records, including primary tumor, preoperative Frankel score, other bone metastases, preoperative Karnofsky performance status (KPS), number of involved vertebrae, pathological fracture metastasis site, serum albumin, sphincter dysfunction and the time of developing motor deficits before surgery. Survival data were obtained from medical records or via telephone follow-ups. Univariate and multivariate predictors of overall survival for each group were assessed using the Cox proportional hazards model.

The median postoperative survival time was 6.0 ± 0.6 months (95% confidence interval [CI] 4.8-7.2) in patients with SSM and 7.0 ± 1.0 months (95% CI 5.1-8.9) in patients with MSM (P = 0.238). The difference in survival was not significant between groups. Furthermore, univariate analysis showed that the number of spinal metastases had no significant association with survival (P = 0.075). Primary tumor (P = 0.004) and preoperative KPS (P < 0.001) were independent prognostic factors in the whole cohort; primary tumor (P = 0.020), time of developing motor deficit (P = 0.041) and preoperative KPS (P = 0.038) were independent prognostic factors in patients with SSM; while preoperative KPS (P = 0.001) and serum album level (P < 0.001) were independent prognostic factors in patients with MSM.

The number of spinal metastases has not proven to be useful in predicting the prognosis for patients with MSCC. Consequently, more aggressive operations should be considered for patients with multiple spinal metastases.