Grading brain and spinal cord tumours
Grading describes how the cancer cells look compared to normal, healthy cells. Knowing the grade gives your healthcare team an idea of how quickly the cancer may be growing and how likely it is to spread into surrounding tissues in the brain or spinal cord. The grade can help the healthcare team predict future outcomes (prognosis) and how the cancer might respond to treatment.
To find out the grade of a brain or spinal cord tumour, a pathologist looks at a tissue sample under a microscope. They look at how different the tumour cells look from normal cells (called differentiation) and other features of the tumour such as the size and shape of the cells and how the cells are arranged.
WHO CNS5 classification system
The most common grading system for brain and spinal cord tumours is part of the World Health Organization (WHO) CNS5 classification system. It assigns the appearance of the cells a grade from 1 to 4. The more normal the cells look, the lower the grade. The more abnormal the cells look, the higher the grade.
Grade 1 tumours are non-cancerous (benign). They have cells that look like normal cells under the microscope. They grow slowly, are less likely to spread into surrounding tissues and have a good long-term prognosis. Grade 1 tumours are also called low-grade tumours.
Grade 2 tumours have cells that look a bit abnormal when compared to normal cells. They grow slowly, but they can grow larger and start to spread into the surrounding tissues.
Grade 3 tumours are cancerous (malignant). The cells look abnormal and can spread to other parts of the brain and spinal cord.
Grade 4 tumours are the most aggressive type of cancerous brain or spinal cord tumour. The cells are very abnormal. They grow quickly and spread into the surrounding tissues. Grade 4 tumours are also called high-grade tumours.
Different gene alterations in a tumour type may affect the grade that a tumour is given. For example, some types of astrocytoma with an MYB-altered gene have a lower grade than astrocytoma with an IDH-mutant gene.
Different grades can be given to the same type of tumour. For example, astrocytoma (IDH-mutant) can be given a grade of 2, 3 or 4. Meningiomas can be grade 1, 2 or 3.
Some brain and spinal cord tumours do not have a grade assigned during diagnosis. This is because they may be very responsive to treatment even if they have a high grade, but giving them a low grade would not reflect how aggressive the tumour can be if it isn’t treated.
The grade of a brain or spinal cord tumour can change over time from a low grade to a higher grade. When this happens, it’s called a malignant transformation. Changes in tumour grade happen more often in adults than in children.
Your trusted source for accurate cancer information
With support from readers like you, we can continue to provide the highest quality cancer information for over 100 types of cancer.
We’re here to ensure easy access to accurate cancer information for you and the millions of people who visit this website every year. But we can’t do it alone.
Every donation helps fund reliable cancer information, compassionate support services and the most promising research. Please give today because every contribution counts. Thank you.