Clinical Outcomes Following Dose-Escalated Proton Therapy for Skull-Base Chordoma

Area of Science:

• Radiation Oncology
• Neurosurgery
• Medical Physics

Background:

• Skull-base chordoma is a rare bone tumor requiring complex treatment.
• External-beam proton therapy (PT) offers potential advantages in dose distribution for tumors near critical structures.
• Evaluating the long-term efficacy and toxicity of PT is crucial for optimizing treatment strategies.

Purpose of the Study:

• To assess the effectiveness of high-dose proton therapy (PT) in achieving local control and improving survival for patients with skull-base chordoma.
• To compare outcomes based on surgical resection status and treatment modality (definitive vs. adjuvant PT).

Main Methods:

• Retrospective review of medical records for 112 patients with skull-base chordoma treated with definitive or adjuvant PT between 2007 and 2019.
• Assessment of overall survival, disease-specific survival, local control, and freedom from distant metastasis.
• Grading of radiotherapy toxicities using Common Terminology Criteria for Adverse Events (CTCAE) version 4.0.

Main Results:

• The 5-year actuarial rates for overall survival, disease-specific survival, and local control were 78%, 83%, and 74%, respectively.
• Patients undergoing gross total resection followed by adjuvant PT demonstrated excellent local control (95%) and disease-specific survival (100%).
• No serious acute toxicities (grade ≥3) related to radiotherapy were observed.

Conclusions:

• High-dose PT is effective in achieving favorable 5-year local control rates for skull-base chordoma, outperforming conventional techniques.
• Adjuvant PT following gross total resection yields excellent outcomes with acceptable late complication-free survival.
• Continued follow-up is essential to fully understand the long-term disease control and potential late toxicities associated with PT.