Standard neurobiology textbooks commonly do not contain a chapter on cancer, and the word might not even appear in the index. Its absence cannot be explained simply on the grounds that the subject falls more appropriately within the clinical realm, because you will find chapters devoted to various other nervous system diseases. Could this intellectual blind spot result from the fact that mature neurons, being post-mitotic, do not succumb to the disease? This absence in most texts is curious, considering the severe functional implications. The word is sometimes used metaphorically to connote an unstoppable process of destruction, and indeed some forms of brain cancer present the most dire prognosis of any cancer. But more importantly the neglect of this subject is curious, because on a molecular and cellular level, cancer is the result of biological processes that are at the forefront of modern neurobiological research. These include such current hot-topic areas as intraand inter-cellular signaling networks, regulation of gene transcription, control of cellular differentiation, regulation of cell motility, migration and cell death; the secretion and response to growth factors, and interactions with the vascular and immune systems. Finally, the current enthusiasm and promising research on the use of stem cells for therapeutic treatment of nervous system disease has brought us face-to-face with our ignorance in this area, as we find that many types of stem cells transplanted into the brain form tumors. This issue of Neuron Glia Biology contains a special collection of original research papers on cancer in the peripheral and central nervous system and a review on the subject. These papers are introduced below by Special Feature Editor, Philip Lee.