Could you give me a vivid medical description of how glioblastoma multiforme works?

Mutation and growth: Like all cancers, glioblastoma multiforme (GBM) is an abnormal growth of cells (in this case arising in the brain) triggered by a randomly occurring mutation. The growth causes pressure on normal brain tissue, causing neurologic symptoms that lead to its discovery. It can be treated with surgery, radiation, and chemotherapy with better and better results, but remains incurable.