When a person dies from cancer, the culprit isn't usually the original tumor - it's
metastasis, the spread of cancer cells throughout the body. Now, researchers have managed to package a drug in nanoparticles (a microscopic particle with at least one dimension less than 100 nm) so that it can target these cancer cells without, crucially, interfering with normal cells - and report that they've stopped cancer cells from spreading in mice. Nanoparticle research is currently an area of intense scientific research, due to a wide variety of potential applications in biomedical, optical, and electronic fields.
Source: http://news.sciencemag.org/biology/2015/01/nanoparticle-drug-stops-cancer-s-spread-mice