Brain tumors are named after the type of cell they arose from and where they formed. They are also graded on a scale of I to IV, based on their
appearance under the microscope and likelihood of growing and spreading. In general, the higher the grade, the more aggressive and dangerous the
tumor. Overtime, tumor cells often change becoming more malignant, and when tumors recur, they often come back as a high, more aggressive grade.
As scientists learn more about the genetics of tumors, they are able to identify subtle differences between tumors of the same type and grade that
affect how these tumors behave and how they may respond to different treatments. Your doctors may use such genetic information to help draw up a
Tumor Grading System (from PDQ patient):
- Grade I (low-grade) . The tumor grows slowly, has cells that look a lot like normal cells, and rarely spreads into nearby tissues. It may be possible to remove the entire tumor by surgery.
- Grade II . The tumor grows slowly, but may spread into nearby tissue and may recur (come back). Some tumors may become a higher-grade tumor.
- Grade III. The tumor grows quickly, is likely to spread into nearby tissue, and the tumor cells look very different from normal cells.
- Grade IV (high-grade). The tumor grows and spreads very quickly and the cells do not look like normal cells. There may be areas of dead cells in the tumor. Grade IV brain tumors are harder to cure than lower-grade tumors.