Dendrimers are prepared with a level of control not attainable with most linear polymers, leading to nearly monodisperse, globular macromolecules with a large number of peripheral groups. As a consequence, dendrimers are an ideal delivery vehicle candidate for explicit study of the effects of polymer size, charge, composition, and architecture on biologically relevant properties such as lipid bilayer interactions, cytotoxicity, internalization, blood plasma retention time, biodistribution, and tumor uptake. Over the last several years, substantial progress has been made towards the use of dendrimers for therapeutic and diagnostic purposes for the treatment of cancer, including advances in the delivery of anti-neoplastic and contrast agents, neutron capture therapy, photodynamic therapy, and photothermal therapy. The focus of this review is on dendrimer developments from the last four years for oncological applications, with emphasis on distinct architectures and the biological responses these structures elicit.