Prognostic factors and survival in low grade gliomas of the spinal cord: A population-based analysis from 2006 to 2012

Purpose: Primary spinal cord tumors are rare, and evidence-based management of these patients remains a source of controversy. This study used a large cohort of low-grade spinal cord astrocytomas to determine the effectiveness of prognostic factors and survival. Methods: The Surveillance, Epidemiology, and End Results (SEER) cancer registry was used to identify patients with WHO grade I-II primary spinal cord astrocytomas from 1973 to 2012; however, patients before 2006 were excluded due to ambiguity diagnosis. Univariate and multivariate Cox proportional hazard models were created to compare survival across covariates and summarized using the Kaplan-Meier method. Results: A total of 561 patients with low-grade glioma (astrocytoma) were identified. Among these, 15.5% of patients received a gross total resection (GTR), 26.1% subtotal resection (STR), and 46.2% unidentified extent of resection. 59.4% did not receive any radiation therapy at any point of the treatment course, while 40.6% underwent radiation therapy. In our cohort, only patients with GTR demonstrated statistically improved survival (HR: 0.22, P < 0.001). Patients with STR had nearly identical survival compared to patients with no surgery (HR: 0.98), and radiotherapy was associated with increased odds of mortality (HR: 1.47, P < 0.001). Multivariate analysis demonstrated a significant survival benefit among patients with younger age, GTR and absence of radiotherapy. Histologic grade did not statistically impact survival. Conclusion: Our study suggests that GTR results in improved survival among patients with low-grade gliomas within the spinal cord. Future, considerable data research efforts will aim to better define the role of radiotherapy and tumor grading in this patient population.