This study will assess cognitive function in patients with a primary brain tumour treated with radiation therapy (RT) to generate radio-sensitivity and volume effect parameters for the development of cognitive dysfunction. All types of brain tumours apart from glioblastoma will be included.

RT is fundamental in the treatment of primary brain tumours. RT contributes to improved local control and prolonged progression-free survival in patients with a broad range of tumour types. Irradiation to the normal brain may lead to cognitive impairments. Clarifying the nature and severity of impairment in adult RT-treated brain tumour patients, including region-specific effects, are important for optimal utilization of novel conformal RT technologies such as proton therapy.

The study is a prospective nationwide study including approximately 300 brain tumour patients from the Danish Center of Particle Therapy and the four Neuro Oncology Centers in Denmark.

The patients will be assessed with a comprehensive battery of standardized cognitive tests and complete a questionnaire (PRO's). They will do this prior to RT treatment and 1, 3, 5 and 10 years afterwards. The PRO's includes measures on quality of life, fatigue, sleep, depression, anxiety, and socio demographics. The standardized tests are: Trail making Test (TMT); Hopkins Verbal Learning Test (HVLT); Controlled Oral Word Association Test (COWAT) - Animals and S; Coding and Digit Span from WAIS-IV. The correlation between cognitive scores and RT dose-volume parameters to specific areas in the brain will be tested.

This study will elucidate the dose-response relationship in radiation-induced damage to substructures of the brain such as hippocampus, thalamus, temporal and frontal lobes that will allow the clinician to prioritize these structures in planning of proton radiotherapy.

Inclusion Criteria:

• 18 years or older and Danish speaking.
• Performance status WHO 0-2
• Capable of cooperating on testing
• Tumour histology (WHO 2016 classification) of the following types: anaplastic astrocytoma (IDH mutant), diffuse astrocytoma (IDH-mutant), gemistocytic astrocytoma (IDH mutant), diffuse astrocytoma (NOS), oligodendroglioma, meningioma, medulloblastoma (NOS), pituitary adenoma, other brain tumours including skull base sarcomas

Exclusion Criteria:

• Glioblastoma
• Performance status 3-4 (Karnofsky Performances of 60 or less)

The patients will be diagnosed with a primary brain tumour and referred to radiation therapy.