Single-stage posterior decompression and stabilization for metastasis of the thoracic spine: prognostic factors for functional outcome and patients' survival

Background context: There are limited data analyzing radiological and clinical factors for the functional outcomes of surgery for spinal metastasis. Also, there are few studies to investigate the relationship between the functional outcome and the patients' survival. Thus, analysis of both functional outcomes and the survival with their relationship in a possibly homogenous group of patients is worth being reported.

Purpose: To assess treatment outcomes of single-stage posterior decompression and stabilization (PDS) with or without corpectomy for thoracic vertebral metastases and to analyze factors affecting both the functional outcome and the patients' survival after the surgical intervention.

Study design: Retrospective observational study.

Patient sample: A consecutive series of 105 patients, who underwent the previously stated surgery for metastatic spinal cord compression (MSCC) of thoracic spine, were included and retrospectively analyzed.

Outcome measures: The postoperative functional outcomes were evaluated using visual analog scale and Frankel grade at postoperative 2 weeks, and all patients were followed for survival analysis.

Methods: An institutional database was searched to identify all patients who underwent single-stage PDS for thoracic metastatic spinal tumors between March 2002 and June 2010. Demographic data as well as preoperative and postoperative medical conditions were collected from medical records. Radiological findings were confirmed on electronic archive. Survival data were obtained either on medical records or with a reference to governmental cancer registry system.

Results: Postoperative pain improvement was more evident in patients receiving anterior column reconstruction and four or more levels of fixation (p=.02 and <0.01, respectively). Twenty-one patients (20%) showed improvement of the Frankel grade, and 10 of 21 Frankel C patients became ambulatory. The preoperative Karnofsky Performance Scale (≥70) and ambulatory status were significant predictors for the postoperative ambulatory function. After surgery, the median overall survival of the patients was 6.0 months. In the univariate analysis, the patient's age (younger than 60 years), type of primary cancer (ie, moderate and slow growth), no visceral metastases, less than three levels of spinal metastases, and postoperative adjuvant therapy were positively significant for the patients' survival (p<.05). In the multivariate analysis, limited (less than three levels) spinal metastases and postoperative adjuvant therapy were proven to significantly prolong the patient's survival (hazard ratios of 0.53 and 0.48, respectively, p<.05). Although the functional outcomes did not directly influence the patients' survival, the patients with better functional outcome showed increased chance of receiving postoperative adjuvant therapy (p<.01).

Conclusions: Single-stage PDS with or without corpectomy effectively improved the functional status of patients with MSCC of the thoracic spine and also afforded the patients to have more chances of postoperative adjuvant therapy, which was significant for patients' survival. Therefore, we suggest that the role of surgery in the management of MSCC could be not only a symptomatic palliation but also a strategy to prolong patients' survival.