Extent of Surgical Resection as a Predictor of Tumor Progression in Skull Base Chordomas: A Multicenter Volumetric Analysis

Introduction: Skull-base chordomas are aggressive tumors with a propensity for recurrence/progression. Even with standard of care (SoC), 5-year recurrence rates are variable (19%–54%). This high recurrence/progression rate correlates with increased morbidity and mortality. We sought to analyze a multicenter cohort of skull base chordomas to identify predictors of progression in patients receiving SoC. Methods: The [Blinded]-Neurosurgery data registry was queried for skull base chordomas treated from 2008–2020. Patients with the histopathologic diagnosis of chordoma were included. The cohort was composed of patients with preoperative and postoperative magnetic resonance imaging. Tumor volume and radiologic characteristics were obtained from axial T2 sequences using a Digital Imaging and Communications in Medicine viewer. Survival analysis was performed using Kaplan-Meier method, and time-to-event multivariate regression was performed to identify independent predictors of progression. Results: The cohort included 195 patients, of which 66 patients met inclusion criteria; median age was 44, and 28 (42%) were females. Fifty-four (82%) received SoC, 7 (11%) resection only, and 5 (8%) radiotherapy only. Median preoperative and postoperative tumor volumes were 11.55 cm³ (0.33–54.89) and 0.34 cm³ (0–42.52), respectively. Recurrence rate with SoC was 37%. Postoperative tumor volume (P = 0.010) correlated with progression. A postoperative volume of >4.9 cm³ (P = 0.044), ≤81.3% of tumor resection (P = 0.02), and lower-clivus location (P < 0.005) correlated with decreased time to progression. Conclusions: Skull base chordomas can be challenging to resect. Even though maximal resection and radiotherapy improve rate of tumor progression, many of these lesions eventually recur. We have identified a postoperative tumor volume of ≥4.9 cm³ and extent of resection of ≤81.3% in this cohort as predictors of progression in patients receiving SoC.