Improvement of Local Control in Skull Base, Spine and Sacral Chordomas Treated by Surgery and Protontherapy Targeting Hypoxic Cells Revealed by [18F]FAZA) PET/CT Tracers

Improvement of Local Control in Skull Base, Spine and Sacral Chordomas Treated by Surgery and Protontherapy Targeting Hypoxic Cells Revealed by [18F]FAZA) PET/CT Tracers: Conditions:   Skull Base Chordoma;   Vertebral Chordoma

Interventions:   Procedure: Surgery;   Radiation: Protontherapy

Sponsor:   Institut Curie

Improved local control of chordoma initially treated with surgery or not, thanks to adjuvant radiotherapy oriented by conventional imaging Computed Tomography /Magnetic Resonance Imaging (CT / MRI) and guided by the [18Fluor] ([18F]) Fluoroazomycin Arabinofuranoside (FAZA) Positron Emission Tomography / Computed Tomography (PET / CT) to target the radioresistant hypoxic cells.

Condition	Intervention	Phase
Skull Base Chordoma Vertebral Chordoma	Procedure: Surgery Radiation: Protontherapy	Phase 2

Arms

Assigned Interventions

Experimental: [18F]FAZA PET/CT In residual chordoma tumors after surgery, Investigators propose a protontherapy guided by conventional imaging (CT/MRI) and a boost guided by FAZA PET/CT, in order to target the hypoxic zones and to increase the dose in an adequate manner, which could result in improving long-term local control and reducing complications.

Procedure: Surgery The operative approach and operating time will be performed according to neurosurgical practices (for head and neck) or surgical orthopaedic team (for sacrum) depending on the location, the extension and the relationship of the lesion to critical structures. The surgery can be macroscopically complete or incomplete. Radiation: Protontherapy Radiotherapy will be done with the Cyclotron, for a total dose of 78 Gray Relative Biological Effective (Gy RBE) - 70 Gy RBE to the tumor bed and macroscopic volume and 8 Gy RBE to the the hypoxic component volume, delivered in 39 fractions spread over 67 days.

Detailed Description:

Due to the close contacts of the lesion with the neurovascular structures, in the case of skull base chordoma and mobile spine, surgery is often incomplete. On the contrary, surgery of the sacral region (for which the block excision is often possible) brings a better therapeutic outcome. Radiotherapy with high-dose supplement improves the outcomes for all these lesions.

Intratumoral hypoxia is a primary factor of radioresistance, it's known since long by radiation oncologists. [18F]FAZA gives an image of the hypoxic volume target. Investigators propose to increase the radioactive dose in the hypoxic volume target but in order to succeed, radiation oncologists have to precisely identify this hypoxic volume. Radiation oncologists would increase of 10% the radioactive dose that will allow us to improve local control at 3 years of 15% without any additional side effect.



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