Chordoma of the Skull Base: A National Cancer Database Analysis of Current Practice Patterns and Outcomes

Abstract

Chordomas of the skull base are aggressive locally destructive tumors that arise from the remnants of the fetal notochord. Current guidelines recommend maximal safe surgical resection followed by adjuvant radiation therapy. However, because of the rarity of these tumors, the optimal radiotherapeutic regimen regarding dose and modality is unclear. The National Cancer Database (NCDB) was queried from 2004 to 2016. Data from adult patients were extracted, including tumor characteristics, comorbidity indices, and details of treatment (surgery, radiation, and chemotherapy). The primary outcome of interest was overall survival (OS), which was evaluated for specific treatment cohorts using Cox univariate and multivariate regression constructs along with associated survival curves. We identified 798 patients with a diagnosis of skull base chordoma. Mean OS in this cohort was 9.57 years. Most patients received surgical resection (89.1%), with 53.9% receiving radiotherapy and 6.5% receiving chemotherapy. After adjusting for baseline characteristics using multivariate regression, advanced age and increased tumor size were associated with decreased OS. Surgical resection was associated with increased OS, whereas neither radiotherapy nor chemotherapy was associated with OS. However, in patients who did receive radiation, dosage >6000 cGy was associated with increased OS (hazard ratio, 0.51; P= 0.038); OS did not vary significantly between traditional and proton-based methods. Our multi-institutional analysis supports the use of partial and radical surgical resection to improve survival in patients with skull base chordomas. Among patients who receive radiotherapy, higher radiation dose is associated with improved survival.