Phase II Clinical Trial of Low-intervention Using Hypofractionated Protontherapy in Chordomas and Chondrosarcomas of the Skull Base
The project is planned as a phase II clinical trial with a low level of intervention, for the prospective evaluation of the clinical results of radical or adjuvant treatment by proton therapy in chordomas and chondrosarcomas of the skull base using hypofractionation schemes in 5 fractions, with the aim of consolidating the scientific evidence that exists with high-precision techniques with photons, increasing this evidence by adapting this treatment scheme to the proton technique. In addition, a cross-sectional prospective evaluation of the quality parameters of the dosimetry of hypofractionated proton therapy and an evaluation of the quality of life of these patients will be carried out. * Primary Objective 1. \- Toxicity according to CTCAE-v5 criteria 2. \- Local control determined by Magnetic Resonance with Gadolinium. * Secondary Objectives 1. To evaluate the quality of life of the patients, 3 months after the end of the treatment, using a specific questionnaire. 2. To evaluate the dosimetric benefits using techniques that allow an improvement in the dose gradient, improving the coverage of the CTV (Clinical Tumor Volume) and decreasing the dose in surrounding risk organs.
• With a baseline classification on the Karnofsky performance status scale ≥ 70%.
• With confirmed histological diagnosis of chordoma or chondrosarcoma of the skull base.
• Who have signed the specific informed consent of the protocol, agreeing to participate in it.
• With a maximum tumor size of 50 cc.
• Whose relationship to organs at risk (OARs) allows compliance with the necessary dose restrictions to receive hypofractionated proton therapy in 5 fractions.
⁃ Patients included in the study must meet dosimetric parameters that include:
• Tumor CTV coverage of at least D95\>90%.
• Correct compliance with the dose restrictions, at least in the nominal scenario, for critical organs (optic pathway, brain stem and spinal cord) according to the guidelines published and available in the literature:
⁃ Dose contnstraints for 5 fractions:
⁃ Optic Nerves: D0.03cc ≤ 25 GyRBE, V23.5 \< 0.5cc. Chiasm:D0.03cc ≤ 25 GyRBE, V23.5 \< 0.5cc. Brainstem:D0.03cc ≤ 31 GyRBE,V23 \< 0.5cc. Spinal Chord: D0.03cc ≤ 30 GyRBE, V23 \< 035cc.