Cancer patients often present with localized disease. Yet, surgical eradication or radiation treatment is not always possible or meaningful. Site-directed drug targeting is one way of local or regional antitumor treatment. Magnetically controlled drug targeting is one of the various possibilities of drug targeting. This technology is based on binding established anticancer drugs with ferrofluids that concentrate the drug in the area of interest (tumor site) by means of magnetic fields. Then, the drug desorbs from the ferrofluid and enfolds its mechanism of action.