The number of cylinders that constitute a carbon nanotube (CNT) can vary from only one to several ones, giving rise to different kinds of CNTs, namely single-walled CNTs (SWCNTs), double-walled CNTs (DWCNTs), up to generic multiwalled CNTs (MWCNTs). The use of carbon nanotubes, in particular in anticancer drug delivery, is really promising despite the fact that some actual limitations are slowing down the development of this technology. The continuous development of the carbon cage functionalization, improving CNT dispersibility and biocompatibility, paves the way to their use in clinics. However, two important topics still are under debate among scientists in the field, namely this material's toxicity, and its cellular uptake mechanism. This chapter overviews these questions, and a full description of the existing literature on the application of CNTs in anticancer drug delivery is given.
