Grading brain and spinal cord tumours
The grade is a description of how the cancer cells look and act compared to normal cells. To find out the grade of a brain tumour, the pathologist looks at a tissue sample from the tumour under a microscope. The pathologist gives a brain tumour a grade from 1 to 4. The lower the number, the lower the grade.
How different the cancer cells look is described as differentiation.
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 2 brain and spinal cord tumours are low grade and are often called benign tumours.
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 4 brain and spinal cord tumours are high grade and are called malignant tumours.
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 might come back (recur) as a high-grade tumour.
Knowing the grade gives your healthcare team an idea of how quickly the cancer may be growing and how likely it is to spread. This helps them plan your treatment. The grade can also help the healthcare team predict your prognosis and how the cancer might respond to treatment.
American Cancer Society. Brain and Spinal Cord Tumors in Adults. 2014: http://www.cancer.org/acs/groups/cid/documents/webcontent/003088-pdf.pdf.
Clark V, Moliterno Gunel J, Gunel M . Molecular biology of central nervous system tumors. DeVita VT Jr, Lawrence TS, & Rosenberg SA. Cancer: Principles and Practice of Oncology. 10th ed. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins; 2015: 96:1403-1411.
National Cancer Institute. Adult Central Nervous System Tumors Treatment for Health Professionals (PDQ®). 2016: http://www.cancer.gov/types/brain/hp/adult-brain-treatment-pdq#section/all.