There are no generally useful staging systems for most brain tumors, although some are classified according to grade. With brain stem glioma, for example, tumors in the higher region—the midbrain—are more likely to be lower grade and have a higher chance of long-term survival than tumors lower down in the pons and the medulla (40 percent versus less than 20 percent).
A variety of staging systems have been used for medulloblastoma. The Pediatric Oncology Group and the Children's Cancer Study Group have divided this tumor into low and high stages. Essentially, low-stage implies smaller tumors without metastasis , in which the tumor remaining after surgery is smaller than 1.5 cubic cm. High-stage refers to larger tumors with evidence of metastatic spread or brain stem involvement and tumor over 1.5 cubic cm remaining after surgery.
