Predictors of quality of life improvement after surgery for metastatic tumors of the spine: prospective cohort study

Abstract

Background context: Surgical decompression and stabilization followed by radiosurgery represents an effective method for local tumor control and neurologic preservation for patients with metastatic epidural spinal cord compression (MESCC). We have previously demonstrated improvement in health-related quality of life (HrQOL) after this combined modality treatment ("hybrid therapy").

Purpose: The current analysis focuses on delineation of patient-specific prognostic factors predictive of HrQOL change after combined surgery-stereotactic radiosurgery (SRS) treatment of MESCC.

Study design: This is a prospective, single-center, cohort study.

Patient sample: One hundred and eleven patients with MESCC who underwent separation surgery followed by SRS were included.

Outcome measures: Prognostic factors associated with improved patient-reported outcome (PRO) measures.

Methods: Patient-reported outcome tools, that is, Brief Pain Inventory (BPI) and MD Anderson Symptom Inventory-Spine Tumor (MDASI-SP), both validated in the cancer population, were prospectively collected. Numeric prognostic factors were correlated with PRO measures using the Spearman rank correlation coefficient. Categorical prognostic factors were correlated with PRO measures using the Wilcoxon two-sample test (for two categories) or the Kruskal-Wallis test (for three or more categories). All statistical tests were two-sided with a level of significance <.05 for correlation of prognostic factors with PRO constructs and a level of significance <.0014 for correlation of prognostic factors with PRO items. Statistical analyses were done in SAS (version 9.4, Cary, NC, USA).

Results: One hundred and eleven patients were included in this analysis. Patients with lower preoperative Medical Research Council (MRC) motor scores experienced a greater decrease in symptom interference (BPI interference construct (p=.03) and individual functional measures including general activity (p=.001), walking (p=.001), and normal work (p=.006)). Lumbar location was associated with better outcomes than cervical or thoracic as noted on the BPI pain experience construct (p=.03) and MDASI-SP interference (p=.01) and core symptom (p=.002) constructs. Patients with American Spinal Injury Association (ASIA) scores of C or D benefit more than those with ASIA E on BPI interference construct (p=.04). Patients with higher Eastern Cooperative Oncology Group (ECOG) scores at presentation benefit more than those with low ECOG scores on MDASI-SP interference construct (p=.03). Women benefit more than men on BPI interference (p=.03) and pain experience (p=.04) constructs. Patients with prior spinal surgery at the current level of interest benefit less than those who are naïve surgical patients in MDASI-SP interference construct (p=.04).

Conclusions: Delineation of patient characteristics associated with HrQOL improvement provides crucial information for patient selection, patient education, and setting treatment expectations. For patients with MESCC treated with hybrid therapy using surgery and radiosurgery, the presence of neurologic deficits and diminished performance status, lumbar tumor level, and female gender were associated with greater PRO improvement.

Keywords: HrQOL; MESCC; PRO; Prognosis; Separation surgery; Spine tumor.