From The Economist:
Journalists sometimes joke that the ideal headline for a science story would be something like “Black holes cure cancer”. Sadly, it will never happen. “Nanotechnology cures cancer”, though, is a pretty good runner-up, and that might just turn out to be true.
In fact, nanoparticles (ie, objects whose dimensions are measured in nanometres, or billionths of a metre) have been used to treat cancer for some time. But these treatments are mainly clever ways of packaging existing drugs, rather than truly novel therapies. For instance, Doxil, a medicine used to treat ovarian cancer, is wrapped up in naturally occurring fatty bubbles called liposomes. Taxol, a common breast-cancer drug, is similarly packaged with naturally occurring blood proteins in a product called Abraxane. In both, the packaging aids the delivery of the drug and reduces its toxic side-effects.
Now, however, a second generation of nanoparticles has entered clinical trials. Some are so good at hiding their contents away until they are needed that the treatments do not merely reduce side-effects; they actually allow what would otherwise be lethal poisons to be supplied to the tumour and the tumour only. Others do not depend on drugs at all. Instead, they act as beacons for the delivery of doses of energy that destroy cancer cells physically, rather than chemically.
More here.