Tumors in the cauda equina: A SEER analysis of tumor types and predictors of outcome

Cauda equina tumors are histologically diverse. International Classification of Diseases for Oncology (ICD-O3) confers dedicated site code (C72. 1) for cauda equina. This code is excluded during analyses of other primary spinal cord tumors. In this retrospective study, the Surveillance, Epidemiology and End Results (SEER) data for primary cauda equina tumors (PCET, C72. 1) excluding the tumors of spinal meninges (C70. 1) from 1992 to 2015 were reviewed. Demographic characteristics, tumor types, and clinical outcomes were analyzed using univariable analysis. Overall survival was estimated using Kaplan-Meier methods and compared for age, histology and treatment type. 293 patients with PCET met inclusion criteria. The most common tumors comprised schwannoma (32%), myxopapillary ependymoma (21%), malignant ependymoma (22%). The median age at diagnosis was 50 years (range < 1 year to 98 years), 57% of patients were males. 77% of the patients underwent surgery. Median follow up time for these patients was 70 months. Of the 293 patients, 250 (85%) were living at the end of 2015. The cause of death was tumor or CNS related in 15 patients. 136 patients were followed for <5 years, of which 102 were censored and 34 died (11.6%) before 5 years. Using univariable analysis, age at diagnosis (Hazard Ratio, HR 1.05; confidence interval, CI 1.03–1.07; p < 0.001), malignant tumor type (HR 2.88, CI 1.15–7.19, p = 0.0239) and absence of surgical intervention (HR 2.54, CI1.26–5.11, p = 0.0092) were predictors of increased mortality. Although most patients did well, older age and lack of surgical intervention were associated with worse survival.