Proton Dose Escalation for Patients With Atypical or Anaplastic Meningiomas

The trial intends to optimize treatment for grade II and grade III (atypical or anaplastic) meningioma. Standard treatment for atypical or anaplastic meningioma is surgery. For grade III (anaplastic) meningiomas, post-operative radiotherapy would be performed in all cases using standard fractionation schedules to a total dose of ~60 Gy. For grade II (atypical) meningiomas, although some small patient datasets support early onset of radiotherapy, the standard treatment is still to irradiate if tumours are recurrent or if resection was macroscopically incomplete. Total doses of 54 to ~60 Gy are applied using standard fractionation schedules.

A major problem of the treatment of atypical or anaplastic meningioma is that beyond surgery and radiotherapy, there are only experimental treatment options and the probability of local recurrences is 50-100% within the first 5 years for grade II and grade III meningioma.

The present trial has been developed to evaluate efficacy of a dose-intensified radiotherapy treatment schedule for incompletely or not resected meningioma to a total dose of 68 (grade II) or 72 Gy (grade III). To minimize normal tissue toxicity, the boost dose or the complete radiotherapy is applied using protons. The expectation is a higher recurrence-free survival compared to previous reports on outcome of standard dose (60 Gy) radiotherapy.

Inclusion criteria

• histologically confirmed atypical (WHO grade II) or anaplastic (WHO grade III) meningioma with the indication for radiotherapy
• MRI (within 24h post-operative, if not available than with a time interval of ~ 6 weeks) including contrast-enhanced T1 weighted 3D dataset and PET for evaluation of macroscopic tumour (residuum)
• Karnofsky Performance Score ≥ 60, ECOG ≤2
• For women with childbearing potential, (and men) adequate contraception.
• Ability of subject to understand character and individual consequences of the clinical trial
• Written informed consent (must be available before enrolment in the trial)

Exclusion criteria

• refusal of the patients to take part in the study
• previous radiotherapy of the brain
• several manifestations of the meningioma in different regions of the brain or additional spinal manifestations
• distant metastases
• patients who are not suitable for radiotherapy
• known other malignant disease within 5 years before radiotherapy (except tumours that likely do not impact prognosis and likely not require treatment interfering with study therapy, e.g. in-situ carcinoma of the breast or cervix uteri)
• pregnant or lactating women
• patients with non-MRI compatible metal implants, pacemaker or non-MRI compatible external automatic defibrillators
• patients not able to understand character and individual consequences of the clinical trial
• claustrophobic patients
• current participation in another clinical intervention study