Researchers have developed a new test to more easily diagnose medulloblastoma, the most common malignant childhood brain tumor. The test -- which can distinguish between extremely high-risk medulloblastoma cases that need radiation therapy from those that are lower-risk and do not need radiation -- could help pave the way for personalized treatment options for children suffering from the disease. It relies on an antibody-based technique called immunohistochemistry which is widely available in clinical laboratories around the world.