Radiotherapy After Gross Total Resection of Skull Base Chordoma: A Surveillance, Epidemiology, and End Results Database Analysis of Survival Outcomes

Skull base chordoma is a rare and locally destructive malignancy which presents unique therapeutic challenges. While achieving gross total resection (GTR) confers the greatest survival advantage, the role of adjuvant radiotherapy (RT) for patients who receive GTR remains unclear in the absence of prospective trials. Here, we aim to assess the effect of RT on survival outcomes in skull base chordoma patients who receive GTR by utilizing the Surveillance, Epidemiology, and End Results (SEER) database. Patients with diagnostic, primary site, and resection codes specific for chordoma, skull base, and GTR, respectively, were queried in the SEER database (2000–2018). Kaplan-Meier curves (log-rank test) were constructed and Cox proportional hazards models were used to assess survival outcomes. A total of 115 skull base chordomas undergoing GTR were identified, of which 37 (32%) received no RT and 78 (68%) received RT. Median follow-up was 55.00 months (range: 0.00–227.00). Overall survival (OS) of patients with GTR was 85% and 70% at 5 and 10 years, respectively. Multivariate Cox proportional hazard analysis among chordoma patients undergoing GTR found age ≥65 (P < 0.01) was associated with poorer OS outcomes. RT appeared to trend toward offering benefit in terms of OS in patients after GTR, however this did not achieve statistical significance in the adjusted model (HR = 0.51, CI = 0.23–1.16, P = 0.09). When comparing, disease-specific survival was also not improved in patients undergoing RT (HR = 0.58, CI = 0.23–1.46, P = 0.25). It remains unclear whether RT after GTR of chordoma improved survival outcomes among SEER database patients.