Nanoemulsions are also called mini-emulsions, submicrometric emulsions or ultrafine emulsions, ranging in size from 5-500 nm. Highlighted in the literature by some reports on nanoemulsion testing and biotechnological properties of EOs from Cymbopogon citratus, Citus sinensis and Citrus limon, the use of natural agents alone or in combination with synthetic material seems promising to prevent, delay, halt or reverse carcinogenesis. The anticarcinogenic properties of these compounds have received much attention. Natural products from all classes of terrestrial and marine micro- and macro-organisms continue to play a vital role in drug discovery, including the search for new cancer agents. Indeed, of a total of 175 small molecules approved as anticancer drugs in Western medicine between 1940 and 2014, approximately 50% were either obtained directly from microorganisms and macroorganisms or derived synthetically from natural lead molecules. Thus, this book presents an integrative review of the content regarding the anticancer effects of natural products.