Grades of brain and spinal cord tumours

The grade of a brain tumour gives doctors an idea of how the tumour might behave.

Brain tumours are put into groups according to how quickly they are likely to grow. There are 4 groups, called grade 1 to 4.

What is the grade of a tumour?

Grading is a way of dividing tumour cells into groups based on how the cells look. To find out the grade, an expert doctor called pathologist looks at a sample of brain tumour cells under a microscope. 

The more normal the cells look, the lower the grade. The more abnormal the cells look, the higher the grade.

Grade 1 and 2 tumours are low grade. Grade 3 and 4 tumours are high grade.

Grade 1

The cells look very like normal cells. They are usually slow growing and less likely to spread. 

Surgery is usually the only treatment you need for a grade 1 brain tumour.

Grade 2

The cells look less like normal cells. They are usually slow growing but can grow into the nearby brain tissue.

Grade 2 tumours are more likely to come back after surgery and some can develop into a malignant tumour. 

Grade 3

The cells look more abnormal. They can spread to other parts of the brain and the spinal cord. You are more likely to need radiotherapy and chemotherapy after surgery.  

Grade 4

The cells look very abnormal. These are the fastest growing tumours. They often come back after treatment and can spread to other parts of the brain and sometimes the spinal cord. You usually have treatment with radiotherapy and chemotherapy.   

Benign or malignant

Doctors might refer to some low grade tumours as benign. And high grade tumours as malignant.

This grading system generally works well for most tumours. But for some brain tumours, it isn’t as clear as this.

For example, a slow growing benign tumour can cause serious symptoms and be life threatening if it's in a particular part of the brain. And some low grade astrocytomas can become malignant over time.

Benign tumours are sometimes treated with radiotherapy and chemotherapy. This is to help to control them and reduce the risk of tumour coming back.   

Changing from benign to malignant

Some low grade tumours can develop into a malignant tumour. It is called malignant transformation or progression to malignancy.

For example, a grade 2 tumour could progress to a grade 3 tumour. Or a grade 3 tumour could change to a grade 4. 

Other tests on the cells

Using new techniques, doctors can look at the genes and proteins inside some types of brain tumour cells. These are called biomarker or molecular studies.  

The results of the biomarker studies help doctors decide the best treatment for some types of brain tumours.

There are different types of biomarkers tests you can have. For example, for a type of brain tumour called glioma, you might have tests to look at proteins called:

• IDH
• 1p/19q
• MGMT