"From one cell, oligo begins to grow within the brain. If healthy oligodendrocytes are like delicate roses climbing over a lattice of neurons, the cancerous oligo is a choking vine: In its metastatic stages, it interweaves tendrils through healthy brain tissue so tightly that removing the tumor means removing healthy tissue as well - essentially bulldozing the lattice and the roses with it. Then irradiating the vines. Then spraying the vines with chemicals. And hoping that there aren't any vine roots alive to grow back."