Brain and spinal cord cancers are graded by looking at cancer cells with a microscope. The grade level indicates the degree of aggressiveness (malignancy). Knowing the grade of your cancer is one factor that helps the treatment team in deciding the best course of action to take. The grading is based on the type of cells, how many cells are dividing, and how different the cancer cells look compared to the cells that are normal. For brain and spinal cord cancers, the preferred grading system is based on World Health Organization criteria. Sometimes cancers will have portions with different grades. The cancer is graded on the part with the highest grade.
Grade I: Slow growing: The cells of Grade I cancers may look nearly normal, but for some Grade I cancers the cells are quite unusual looking. In either case, Grade I cancers are less likely to progress or change to a higher grade. For Grade I cancers, cure is sometimes possible with surgical resection alone.
Grade II: Somewhat slow growing. These cancer cells can look close to normal and be difficult to detect. Or, the cells may look a bit unusual. Grade II cancers are likely to enter or spread to nearby normal tissue. Grade II cancers will often come back years after treatment. These cancers tend to progress to higher grades of malignancy.
Grade III: Relatively fast growing and malignant. These cancers tend to come back after treatment. Grade III cancers also tend to progress to higher grade malignancy.
Grade IV: Fastest growing. These cancer cells look strange. They are quite different from normal cells nearby. These cancers are the most malignant and there are often dead cells (called necrosis) in these cancers. New blood vessels are often formed so that the cancer can grow faster. The process of new blood vessels formation is called vascular proliferation or angiogenesis.