This chapter explores what we know about the structure and function of neurons, including the identity and location of adult neural stem cells, the proliferation and specification of neural progenitors, and their suspected involvement in cancer. We begin with a brief review of conventional accounts of neurogenesis and progress toward current issues in the field. Finally, we discuss the potential influence of cancer on the formation and innervation of new neural networks, and the effects of this on metastatic tumour progression. The process of neurogenesis was traditionally believed to occur exclusively during embryonic stages, but recent evidence strongly suggests that neurogenesis occurs in discrete regions of the adult mammalian central nervous system (CNS), and that this process may be upregulated in the presence of cancer. A complex network of biochemical pathways and signalling molecules influence metastatic tumour growth. The dysregulation of these signalling pathways by cancer drives tumour growth and leads to significant symptoms, including pain. Tumour cells secrete growth factors, cytokines, and chemokines and are reported to stimulate adjacent nociceptors. Progressive tumour growth is accompanied by escalating pain behaviours in murine models of cancer-induced bone pain. Neurotrophic factors play an important role in the functionality of nociceptive afferents, and represent a probable link between metastatic tumour growth and pain.