Grading childhood brain and spinal cord tumours

Grading describes how the cancer cells look compared to normal, healthy cells. Knowing the grade gives the healthcare team an idea of how quickly the cancer may be growing and how likely it is to spread. This helps them plan your child's treatment. The grade can also help the healthcare team predict future outcomes (your child's prognosis) and how the cancer might respond to treatment.

To find out the grade of a childhood 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). They also look at other features of the tumour, such as the size and shape of the cells and how the cells are arranged.

The pathologist gives a brain or spinal cord tumour a grade from 1 to 4 based on the grading system developed by the World Health Organization (WHO). The lower the number, the lower the grade.

Brain and spinal cord tumours may contain several grades of cells. The grade of the tumour is determined by the highest grade of cells found even if most of the tumour cells are a lower grade.

Low grade means that the cancer cells are well differentiated. They look almost like normal cells. Lower grade cancer cells tend to be slow growing and are less likely to spread. Grade 1 and grade 2 brain and spinal cord tumours are usually low grade.

High grade means that the cancer cells are poorly differentiated or undifferentiated. They look less normal, or more abnormal. Higher grade cancer cells tend to grow more quickly and are more likely to spread than low-grade cancer cells. Grade 3 and grade 4 brain and spinal cord tumours are usually high grade.

Tumours do not always stay the same. If a tumour changes, the name and grade of the tumour might change. A low-grade tumour might become high grade, or it might come back (recur) as a high-grade tumour.