Retrospective Review of Surgical and Adjuvant Treatment Modalities that Affect Skull Base Chordoma Recurrence Rates

Background: Chordomas are typically slow growing, histologically low-grade extra-axial tumors originating from embryonic remnants of the notochord. However, they are typically locally aggressive, causing lytic bone destruction; when they occur at the skull base, treatment can be challenging given their proximity to vital anatomic structures. Recurrence rate is reported to be as high as 51%, even after postoperative radiation, which makes them difficult to treat.

Objective: To characterize the clinical, surgical, and radiation factors associated with skull base chordoma recurrence rates.

Methods: Retrospective case study of patients with skull base chordoma treated at a single institution from 2002–2015.

Results: A total of 19 patients were included (11M:8F, average age at diagnosis 50.4) and have been followed for an average of 3 years. The most common presenting symptom was diplopia (n = 7, 37%) followed by headache (n = 6, 32%). Chordoma site was characterized as either clival (n = 16, 84%) or cervical spine (n = 3, 16%). All patients underwent surgical resection, either via transcervical +/− transoral approach (n = 4, 21%) or via Stealth-guided expanded endonasal approach (EEA) (n = 15, 79%). Postoperative radiation included proton beam (n = 4, 21%), cyberknife (n = 1, 0.5%), intensity-modulated (IMRT) (n = 11, 58%), or none (n = 3, 16% who refused). At last follow up, 13 patients (68%) remain disease-free or have stable residual tumor, two patients were lost to follow up, and overall recurrence rate was 21% (n = 4). All patients who recurred were male. When analyzed by site, 18% (n = 3) of clival and 33% (n = 1) cervical spinal chordomas recurred. When analyzed by initial surgical resection, 20% (n = 3) of EEA and 25% (n = 1) open approaches recurred. When analyzed by radiation modality, 50% (n = 2) treated with IMRT and 50% with proton beam (n = 2) recurred. Of the four patients who recurred, three died of chordoma-related disease within 1 month to 2 years after recurrence.

Conclusion: In this series of skull base chordomas, we report a tumor recurrence rate of 21%, which is significantly less than what has been previously reported in the literature. Adjuvant treatment with either IMRT or proton beam radiation show a similar recurrence rate. The high mortality rate associated with recurrence highlights the fact that these tumors can be highly aggressive and difficult to treat.