Survival outcomes of intracranial extraventricular neurocytomas: a systematic review and individual patient data meta-analysis.

OBJECTIVE: The rarity of intracranial extraventricular neurocytomas (EVNs) has precluded accurate definition of its surgical characteristics to date. The authors present the first survival analysis of this unique entity that aims to clarify tumor characteristics, surgical outcomes, and efficacy of postoperative adjuvant therapy.

METHODS: A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Searches of the MEDLINE, Embase, Scopus, Google Scholar, and Cochrane Database of Systematic Reviews databases were performed from inception to date. Primary outcomes were progression-free survival (PFS) and overall survival (OS). Prognostic variables were age, sex, tumor consistency, extent of resection, and receipt of postoperative adjuvant therapy. Survival data were analyzed using Kaplan-Meier survival curves and the log-rank test to compare dichotomized cohorts. Multivariate Cox regression models were constructed, interrogated with Schoenfeld residuals, and subsequently utilized to identify independent prognostic factors. Risk of bias was assessed with the Mayo Clinic instrument.

RESULTS: Five hundred fourteen articles were initially retrieved, which was distilled to 10 included articles consisting of 101 cases of intracranial EVNs. The 5-year OS rate was 90.4% (95% CI 81.8%-99.8%) and the PFS rate was 48.6% (95% CI 34.46%-68.8%). The median PFS was 60 months. Patients younger than 50 years of age experienced superior OS (p = 0.03) and PFS (p < 0.01). Gross-total resection (GTR) was superior to subtotal resection (STR) in reducing mortality (p < 0.01). Adjuvant therapy following either STR or GTR did not significantly improve survival.

CONCLUSIONS: Intracranial EVNs are rare tumors that portend a poorer prognosis than central neurocytomas, despite both being WHO grade 2 tumors. Complete surgical extirpation is the cornerstone of management. There is no clearly established role for adjuvant postoperative therapy, but each case should be managed on an individual basis.