Brain tumours are named after the cells in which the cancer first develops, such as neurons (nerve cells), glial cells and meninges.^[1] They can be classified in several ways.

Brain tumours can be benign or malignant:

• Benign brain tumours (called grade I or II) usually grow slowly and are unlikely to spread to other parts of the body. They may grow and affect how the brain works – this can be life-threatening.^[2] An example of a benign brain tumour is a meningioma.
• Malignant brain tumours (called grade III or IV) can grow quickly and may spread within the brain and spinal cord (but usually do not spread further). A malignant brain tumour may be called brain cancer.^[2] The most common malignant brain tumours are called gliomas. These include Astrocytoma IDH-mutant, Oligodendroglioma IDH-mutant and 1p/19q-codeleted and Glioblastoma IDH-wildtype.

Brain tumours can also be classified based on where they start growing:^[3]

• Primary brain tumours start in the brain
• Secondary or metastatic brain tumours start in another part of the body and spread to the brain.

Brain tumours can also be divided based on the changes in the genes (DNA) of the tumour cells, and where the tumour is in the brain.^[3]