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

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 correlate with increased morbidity and mortality. We sought to analyze a multi-center cohort of skull-base chordomas to identify predictors of progression in patients receiving SoC.The [Blinded]-Neurosurgery data registry was queried for skull-base chordomas treated from 2008-2020. Patients with histopathological diagnosis of chordoma were included. The cohort was comprised of patients with pre- and post-operative MRIs. Tumor volume and radiological characteristics were obtained from axial T2-sequences using a DICOM viewer. Survival analysis was performed using Kaplan-Meier method, and time-to-event multivariate regression was performed to identify independent predictors of progression.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 pre-operative and post-operative tumor volumes were 11.55cm3 (0.33-54.89) and 0.34cm3 (0-42.52) respectively. Recurrence rate with SoC was 37%. Post-operative tumor volume (p=0.010) correlated with progression. A post-operative volume of >4.9cm3 (p=0.044), ≤81.3% of tumor resection (p=0.02) and lower-clivus location (p<0.005) correlated with decreased time to progression.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 post-operative tumor volume of ≥4.9cm3 and extent of resection of ≤81.3% in this cohort as predictors of progression in patients receiving SoC.