Patterns of recurrence of skull base chordoma after proton-therapy: a diagnostic and therapeutic challenge

Chordoma are rare tumours of the axial skeleton and may occur at the skull base. It is assumed to arise from notochordal remnants that remain in the axial skeleton during life and may become malignant at any age. The treatment gold standard is surgery, followed by particle radiotherapy (i.e. proton or carbon ion). Because of the location in the skull base, en bloc resection is not possible and macroscopic or microscopic remnants often occur. Locoregional metastasis have been described in literature. To our knowledge, there is no literature describing preferable locations of these locoregional metastases/recurrences. In this retrospective study, all patients that had follow up or were treatment for skull base chordoma in the Maastricht University Medical Centre were analyzed. The goal of the study is to find a pattern in locoregional metastasis and finding a correlation between these metastases and surgical techniques and radiotherapy dose and planning.

Locoregional recurrence of skull base chordoma is due to microscopic tumour seeding in the surgical trajectory which cells do not get a therapeutic radiation dose.

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