Brain tumours and biomarkers

Most types of brain tumour are tested for gene changes. This is called testing for biomarkers or testing for molecular markers.

Molecular markers describe markers, proteins, or changes in the genetic structure of a tumour. The samples are tested for changes in the genes in the tumour cells.

Genes are the instructions cells need to work properly. Genes are inside every cell. Sometimes if the gene is permanently changed, it no longer gives the correct instructions. This gene change is called a gene mutation.

There are different types of genetic changes. These can include the loss of a gene, or part of the gene. These can affect how a cell behaves.

Molecular tests can give doctors more information to help:

• confirm a diagnosis
• find out the type of brain tumour
• know how the tumour may behave over time
• understand which treatment is likely to be most effective.

Types of gene mutations in brain tumours

Different types of brain tumours have different types of gene changes (mutations). The most common types for gliomas include:

• IDH
• 1p/19q
• MGMT
• ATRX
• TP53
• TERT.

Having certain gene changes can mean that the brain tumour may behave differently to what is usually expected. For example, in some cases a low-grade tumour with certain genetic changes could behave more like a higher-grade tumour.

Your doctor may use information from both the grade and the molecular tests to: understand how quickly a tumour might grow help them decide on treatment.

Your doctor can tell you more about whether biomarker tests are helpful in your situation. This type of testing is done on a sample of tumour cells (biopsy).

Some types of biomarkers can be tested with a blood sample. The tests usually need to be sent to a specialist gene laboratory. This means it may take longer to get the results of your tests. The results will help doctors plan your treatment.